New bug found:

In history, when browsing intervals, first page correct (intervals 1-4), then next is intervals 5-8, but if you browse up to 1-4 and back to 5-8 it changes to intervals 4-7. You still can browse between 1-4 and 4-7. If you browse further down, suddenly you lose the first 4 intervals. But it depends of the actual number of intervals, and the interval history can go a bit mad.

Actually it is not a big deal to check the history on the watch, as it is much better on GC, but this bug is still annoying. 

Another one:

Todays swim fit file is not recognized by strava (could be strava fault though, GC can display it), but the .tcx export contains ONLY HR data! Not only for this activity, but for all recorded with Swim 2

Trackpoints look like this:

<Trackpoint>
            <Time>2019-11-22T18:45:50.000Z</Time>
            <HeartRateBpm>
              <Value>72</Value>
            </HeartRateBpm>
            <Extensions>
              <ns3:TPX/>
            </Extensions>
          </Trackpoint>

Usual trackpoint data from FR910XT looks like this

<Trackpoint>
            <Time>2019-11-11T17:13:04.000Z</Time>
            <DistanceMeters>66.0</DistanceMeters>
            <Extensions>
              <ns3:TPX>
                <ns3:Speed>0.4869999885559082</ns3:Speed>
              </ns3:TPX>
            </Extensions>
          </Trackpoint>

You can see, distance is missing from the Trackpoint!

Last length pace, taken from the Swim 2 manual, is:

The average pace for your last completed pool length.

So, what this means is that this metric is updated every time you successfully complete a length. So, for example, in a 25 meters pool, if do the 25 meters in 30 secs, then the last length pace should be 2.00 mins/100 meters.

The problem is that this is not recorded in the activity log, which is pretty reasonable, since it is updated every time you complete a pool length. So in essence it is something like the current speed, but since it as pool and the gps is not active it can only be updated once per length.

Other garmin watches display this correctly, but the swim 2 doesn't seem to do. Let's hope they fix it soon, because it is really useful (at least for me)

FR945 got the pool swim features (in public beta 3.77), including auto rest. In that they already corrected the auto rest bug when activity is stopped/resumed. I hope that swim 2 gets the correction soon.

Personal record saving do not support 33 and 1/3m pools. With 33 and 1/3m pools, 3 lengths are not considered as 100m, but something very close, but not EXACTLY 100m. Wth this bug the watch can not recognize the laps as exact lengths, causing not record saving.

Another bug: the only way to get the backlight permanently on during activity is to disable timeout for both "not during activity" and "during activity"

I've been using my Swm 2 since Christmas with pretty much the same bug pattern:

• butterfly detected as backstroke
• backstroke detected as breaststroke or freestyle

I may be wrong with this, but my impression is that stroke type recognition is triggered very early within a lap (while pushing off the wall or within first few meters), so if I'm still positioned sideways or even slightly backwards out of the turn then recognition fails..

• swimming backstroke or breaststroke distance is registered longer than actual

Same here, too. In my case, other then for freestyle, sometimes the watch misses the turns completely (may be related). Therefore I get wrong times/distances when swimming ***- or backstroke.   

Thanks PG. Related to the above I also see a bug in total interval time calculation even if the swim interval was determined correctly in the first place (auto rest on / running 2.20 beta). In my case start and last wall recognition is pretty good (at least in freestyle); e.g. the switch from swim to rest screen is within ∿2 seconds. Can’t complain about that. However, after a few seconds of rest, some additional 6-10 seconds get added to the swim interval. This happens even if I leave the hand at the wall. In numbers, when swimming 1:30ish / 100m intervals I end up with recorded swim times of around 1:40. 

You can evaluate the auto rest interval time calculation accuracy with an other watch or stopwatch. I made a short test dry, and for me it always calculated the right time. Note, that the watch does not recognize the start of the lap/interval immediately, it continuously performs calculations if you are moving or resting. So the interval seconds do not start at zero, and what you see right at the stop is not carved in stone. After a while, the watch can recognize the actual stopping time, subtract the real starting time. 

I know, it is really frustrating when you see that you swam a good time, and see that the watch corrects it afterwards to the "wrong" direction. If you don't trust the auto rest function, switch it off, and time your intervals manually. You will see if the watch is right or you. I do not say that auto rest times are always correct, but for me they seem to be spot on most of the times. I switch between auto rest off and on, depending on my actual swim and the number of people in the lane.