Yeah, I've found the same problems with my team.

It does seem to be a case of if its hard to sell its easy to buy, as I often can pick up players without any problem, but selling them does seem to be a massive problem - one that is only getting worse as you level up.

I listed players over 1000 times last season to get them sold.

I suggested a few weeks ago to have an option where we could either set them on a list until sold, or set their selling price as low as we want (like set at 0) to get rid - as sacking players sometimes is just stupid when it costs so much.