Fleming just seems to have had this problem with getting games all his career. It's hard to get into a team as a left back, if the team already have one then you're waiting for them to get injured or mess up badly enough to be dropped. Not like other positions where you can change the shape to fit them in, you never need two left backs. He would've played loads more games for City if it wasn't for Elder's form over the last few years. I think he'll need to be patient, he's got a long deal at City and he'll probably get another run as a backup at some point next season when someone gets injured.
I agree about the difficulties of being a LB but I don't think he'll even be our backup next season. If we're serious about a top 6 push we need the backups to be good enough. He needs to go on loan again, and he might even need to drop to L2 to make sure he gets games. But you can't bomb a L1 loan spell and then come back and be part of our squad.