unable to trade large part of pokemon
I've got some pokemon friends which I see most days of the week and we do everything together: raids, battling gyms and now off course trading. But for some reason, which I really cannot figure out, when we open the trading box I can only select like maybe 30% of all my pokemon and the rest is disabled (I have 1490 pokemon in total). We are level 40 and we have all dex entries so that's never the problem. We also delete our traded pokemon afterwards.
For example: I have 6 newly hatched alolan meowths which I wanted to get rid of (so trade) but I simply cannot select them. I remember in the beginning I was able to trade those alolan meowths but somehow its been days in a row now where we trade and I cannot select any of them. Off course in the beginning I did not check if any pokemon were disabled during trading but the last days I started to notice more and there are multiple other examples: I have like 20 machamps from ages ago and yet in the trading box I only see 4 off them. Is this a bug or what am I to think about it? I'm really confused here.