Heart rate (from my wrist) reading too high

Was your cadence also nearly 130 spm when walking? The watch can sometimes get confused by these two frequencies, as your movements will also impact the light signal from the sensors. To get an accurate reading, use a chest strap.

No, my cadence was 117 

I have a similar issue on my F235, as has been mentioned elsewhere. Over half the time the heart rate is too high prior to running, so after it detects the GPS, I shut off and restart the watch. This usually takes care of the issue, but sometimes I have to restart it one or two more times. 

Then after running 10-15 min, I have to recheck to insure it has not started to creep too high again. Sometimes it does get eventually get into cadence lock, around 170+. These excessive high readings will then negatively affect the VO2 max calculations also. 

I have called Garmin about this and, after reviewing the standard recommendations, the representative went through what I understood to be a complete reinstallation of the software. Perhaps it was just a hard reset (I had already done a soft reset). In any case, I lost all my settings and data, and it ultimately did not help the problem. Garmin was surprised that I had the problems at the beginning of the run and that this should not happen, without resorting to a chest strap to resolve the issue. 

So, no answer either, I would certainly be interested in one!

Mine is off like that at times.  These wrist-based heart monitors seem more for entertainment purposes that accuracy. Mine is accurate most of the time but can be way off at others.  I also have a HRM Pro+ that I got on sale about a year ago.  That is accurate so it is what I use for most activities.  I also have an old FR 245 that I have compared to the 255 and the HR sensors are about the same.  I have worn the 245 at the same time as wearing the 255 connected to the HRM, and sometimes the watch will really vary from the HRM.  When I check manually, the HRM is right on.  

I think it is much like the step counting features of these watches.... Gives some information, just don't depend on its accuracy.  Steps, for instance, are counted by the swing of your wrist with an accelerometer.  So if you put your hands in your pockets, no steps are counted.  If you are swinging your hand, like using a leaf blower, hundreds of steps will be registered even if standing still.

We can speculate till end of days about source of this troubles, but was really matter - the OHR and my *** belt on a beta 18.20 works together simultaneously (yes, a green led lits, and external BB is connected) and they both deliver garbage instead of data.

The lights are on as Garmin noted in another comment on this regards that it is for a new feature being developed . If you search a few of the bug reports on the beta platform you can see their comment in that regard .

You are right, i saw those posts and Garmin's feedback though. But it change nothing - on my last LTHR run i got a very frustrated results. With an *** belt and the data taken from space.

Now, on the beta i have a useless watch - no real pace, no real pulse.

And!!! My spotify not works at all.

I've stopped wearing my watch most of the time since the data cannot be trusted.