Slitherine

I have been playing the 1939 Campaign and all core units do not go above 225 points!!!
I have just started the Norway scenario, I am stopping here until I know the bug is fixed.

It's not a bug. In the Grand Campaign the experience per year is caped due to balance reason. Due to the sheer length of the campaign you could else field 5 star units by end of 1940 which would be a bit silly. Every next year of the campaign moves the cap up.

Now when your units are maxed out on experience you can do two following things. Either you start using normal reinforcements to save prestige as your units will be able to recover the lost experience until the end of the year and so amass some prestige for expensive upgrades incoming later or you just buy a few more units and retire your experienced one temporary to train the new units up. This will give you experienced units ready for time when your core size grows or an experienced replacement in case one of your units had an accident.

Thanks Tarrak, for explaining.
Sometimes, people just call out too easily the word bug.

Excellent, great way to handle the experience issue. I thought since it was affecting all unit types, it was bug related.
A great feature I did not realize was in the game; is captured units, until it happened in game play. This is something totally ignored in other games of all types.
Awesome attention to detail on both game play features!!!

There is a maximum experience for each unit for every year of the Grand Campaign:
GC39: 225
GC40: 325
GC41: 375
GC42: 425
GC43E: 525
GC44E/GC45E: 599.