Autolap working during a structured workout

I set up a special sport called "Speed" and have auto lap turned off.  If I do a 10 minute warm up I want to see the pace for the 10 minutes not a mile and a few minutes.

• The new way is more flexible than the old way, while admittedly being more annoying for ppl who liked the old way. The new way gives users a choice where there was none in the past 
• If Garmin changed it back to the old way, then it would annoy ppl who are used to the new way. One analogy is that some users from other platforms think that auto laps should naturally be distinct from manual laps, whereas most users who have only used Garmins couldn’t care less. Who’s to say which way is more correct? You can only say that one is simpler while the other is more flexible. 
• One legit use case for auto laps within a workout is for “long run workouts” — e.g. 4K warmup, 10k half-marathon pace, 1k easy, 10k HM pace, 2k cooldown. In cases like this I’m very happy to use 1k auto laps with a programmed workout. To be fair, you don’t really “need” a programmed workout for something like this

My prediction: this will be a non-issue as soon as enough years pass and most ppl forget (or never knew) what the old behaviour was like. It doesn’t matter which way is “correct”, as with most things that are just a matter of personal opinion or preference — what will ultimately matter is what people are accustomed to. 

Neither.

It is just that for many typical structured workouts, the interval length is less than the auto-lap length, so it doesn't reach the auto-lap trigger.

But on long intervals, it is entirely possible for the auto-lap to trigger a new lap.

I just came from Polar, and I must say they have this nailed pretty well. In their workouts, manual laps are registered, while at the same time (in the background), autolaps are recorded. Afterwards you can then analyze based on either autolap or manual laps.

Starting a new manual lap does not interfere with the automatic laps.

Would be great if Garmin could implement this too!

It took me a couple of interval trainings to figure it out, but now I use a duplicate running profile without autolap.

This will never be as seamless as a built-in solution from Garmin, but you can have independent auto and manual laps if you:

1. Disable auto lap on your activity
2. For stats during an activity: Download Lap+, a full-screen Connect IQ data field app with 6 customizable fields. It supports auto "splits" by time or distance, with 100s of combos of metrics, including lap and split data (e.g. Lap Pace, Split Pace), and data which Garmin doesn't support (e.g. Last Lap Max HR). It also supports split alerts (similar to the built-in lap alert screen) with 3 customizable fields, an optional lap history viewer, and optional color-coding for HR and Cadence fields (by zone)
3. For stats after an activity: Use https://runalyze.com, which syncs with Garmin Connect and lets you divide an activity into arbitrary laps by time or distance.

I am confused. My understanding from what I read from the rest of the answers is that, during a workout, autolap should still be triggered. However, last week I did a workout and I am 99% sure it wasn't. When did this change? There is a good chance at that time my FR935 was still on FW 11.00--it was the 1st day I got this one. I used to have another FR935 until January, but I cannot remember how the behavior was.

No need for confusion. Autolap during workouts is there since the very first release of the 935.

They are triggered at the given distance, when a new lap starts. So it could well be that you did a workout that had shorter laps than your configured autolap distance. E.g. doing a workout with 1km warmup, 10x400m with 400m rest and 1km cooldown will not trigger a 2km autolap. A workout with 2.5km warmup, 10km tempo run and 2km cooldown you would get the following laps after the distances: 2km (autolap), 2.5km (interval ended), 4.5km (autolap), 6.5 (autolap), ...

IMO adding an option to trigger (or not) auto-lap while building a workout, or having the same behaviour as Polar (auto-lap in background while doing a workout) would both be ok and I guess it would not be that expensive to develop!