I am seeing issue 2 as well. I saw this in football manager 23 as well (though not as frequently).
On the image I attached the top training shows the original. After I added training (One time I added something and team bonding).
I am seeing it again right now. Here are the combinations that failed:
Attack / Defending and then match tactics / team bonding
Just changed attacking / defending and it disappeared
Changed 2nd group match practice to rest and all disappeared
Seems to be really any combination makes the training disappear. I added training fail 2nd example to show what I was changing with the combinations above.