In patch notes, they are "adjusting" the slots of ALL PP pets that are untrained due to exploits.
Until then you cannot actually start a PP pet into training mode either as it bugs out due to half of patch being in now already.
If you don't have a fully completed PP pet already, then you have missed the window of opportunity unfortunately.
You can thanks your friendly Atlantic exploiters for this Nerf sledge hammer....
Pet Training: Pre-Publish 97 & Store pets that start Animal Training may have their pet slots updated based on their pet strength and will be given a warning before proceeding. Pets will no longer be able to start training if it will result in the pet being over the max cap.