Companions left at Spire

[Monkbel]

It's pretty clear that companions that are left at Spire are leveling up even though they are not traveling. Not sure what the mechanics is but I can confirm.

There is an interesting bug though regarding "ranks trained this level".
In my case, Verse was left at the spire at level 11. When I came back, she was level 12. I save at the entrance to spire.
If I remove Sirin and add Verse, and then go to trainer, I see that she has 0/5 ranks trained this level and I can train.
If I reload, remove Lantry and add Verse, and then go to trainer, I see that she has 5/5 ranks trained this level. Though ranks are not higher than in the first case.

What's going on?

 

[Monkbel]

Interestingly, one more reload, and here what I see:

if I just come to Verse and add her while removing Lantry, she is actually level 11. I remove her, add Lantry, go to trainer and train my main character, Barik and Sirin. I remove Lantry and add Verse - she is now level 12, well into hundreds!

Is she progressing while I'm training? What's the deal here?

 

[Monkbel]

Interestingly, I found out that if I come to Spire, drop everyone I have in my party, and train my main character, then attach them - they all have gained experience. wow

 

[Monkbel]

So I checked, this happens only when training main character, not when training companions.

 

[Monkbel]

Surprisingly, for Eb, whom I trained exactly never (and never took her in my party), I also see "5/5 ranks trained".