Finally I've managed to reproduce the error and it wasn't too hard after all.
- Stop the cronograph after your run
- reset data and save
- leave the watch on without doing anything more until it goes into standbymode
- switch it off and restart
If you do this then your last race will not have been saved.
If you go into activity info which is what you do most of the time, then your last time will be saved.
If you immediately, without doing anything else, switch the watch off it will also be saved. It seems like it's only when you end up in standbymode that the problem occur. Quite strange. When you save and reset you get the message "save and finish" but apparently it isn't untill you proceed.
I'd say this is a major bug that even if it doesn't happen often shouldn't happen at all. For me it happened after a cross countryrace where I really pushed myheart and lungs so i was quite disappointed when I found that the training info was gone.
Also, I asked in the post above if there is a way to come back from standby mode instead of switching the watch off. Is there or is there not? I think there should be one.
And if there is a standbyfunction in the 625XT, maybe that one too needs to be fixed.