Some trainings missing from the watch

Let me clarify.

You are creating 2 separate Workouts for training day in GC Web / Mobile

Obviously you can see them in the apps but you claim that only "main workout" is available on the watch. Correct?

I guess you send both in the same way. Can you try to create and send them in opposite order? I mean create first "main workout" then "warm-up" Does it help?

But my gut feeling is that you are not following right path.

What do you have when you press this sequence:

Top Right (to access activities) -> Run -> Middle Left (to access Run menu) -> Training  -> Workouts -> now you should see long list of workouts synced to your Watch. What you have here?

I know that attaching images do not work right now, but try type it here.

By the way, if you have always the same Warm-up session (like 10 mins slow pace) you can have it created once and send to device. It will be there waiting for you anytime.

1) Sending in opposite order doesn't change.

2) Sequence: Top Right (to access activities) -> Run ->Altimeter calibration->The watch prompts me the workouts added by me in calendar. In this moment 80% of time the warm-up training is missing. Then I press middle left Training  -> Workouts -> I choose the warm-up. Done it, I re-make the sequence to run the "real" workout of the day.

3) Yes, I have on the watch the warm-up workout and this thing saves me when the watch doesn't get it from the calendar. But the bug is still there, the watch MUST get ALL the workouts scheduled in the calendar via GC web or GC app

2a) Altimeter calibration - well everyday we learn something. I have setup this to auto calibrate overnight, but there is nothing wrong with your configuration.

2b) As I am in the middle of Marathon Plan, I have manually added Running workouts to my Calendar:

After adding those in GC Web, I can see this immediately in GC Mobile

and after sync with Watch I can see those (except my "green" Base)

Interesting thing is that I have NOT sent those workouts to my watch. Those are only in Calendar. hence next point is not good for me.

2c) I understand that my proposed sequence with Middle Left -> Training -> Workouts is actually working for you 

3) Actually there is limit of 25 workouts stored in the watch. 

Why Am I Receiving a Workout Limit Exceeded Message on My Garmin Outdoor Watch? | Garmin Customer Support

Double check if your Warm-Up is Running type.

Maybe delete all workouts from watch and then check again?

If all fails you should contact Garmin Support

BTW, after I have removed all those 4 workouts from Calendar I have again my "green Base" from Marathon Garmin Coach plan.

But I don't send EVERY training to the watcch, I create them in GC web/app, schedule them in calendar and then sync the watch. On the watch there are only a few trainings.

Correct. I have said that too (below watch screenshots) BTW can you see those above?

Maybe there is a bug with Workout names in Calendar and Watch. Could you try to delete all workouts from Watch? Keep them in Calendar

Top Right -> Run -> Middle Left -> Training -> Workouts -> select workout then Top Right -> Delete 

Just done, see what happens next training day.

But sometimes both workouts are in widget calendar, but they don't appear when I start Run