Maybe this is related:
When i first started playing Digimobs, I had a similar issue when i sometimes had 2 of the same Digimon. If i remember right and i probably dont since i was a newb and didnt know how to play very well yet, I would tell the first one to sit, it sits then i tell the second one to do something else and it would be stuck on Sit. The fix was to V pet it.
But related to this, there would sometimes be a glitched egg that couldnt hatch and it would always be in "Sit" and it would force any selected Digimon (i think) into sit and it would spam the chat saying its not ready to digivolve and show the necessary parameters.
Now i remember that for some reason, this only happened with Eggs and Fresh Digimon and my fix was to Digivolve them all into In-Training before creating anymore