I feel this issue (but on FM22)... Managing in Mexico and I have a 22 man squad. The Gold Cup is running so 14 of my 22 man squad aren't available... for 6 matches!
GK: Grey Player
DR: Actual Right Back
DL: Actual Left Back
DCR: Backup Right Back
DCL: Grey Player
DM: Actual DM
MCR: Actual MC
MCL: Backup DM
ST: Actual ST
ST: Actual ST
ST: Grey Player
Bench: All Greys