Hi, I will try to recreate the issue and make a short video showing it but for now it seems like I've fixed it by re-rigging my character.
I think maybe the issue may have been caused by me altering the bone roll for certain bones, although I can't say this for sure.
The problem was that in my walking animation the character's arms swayed in and out at almost a 45 degree angle instead of back and forth like they should've done. Also the legs did not seem to complete their full back and forth swing.
But as I said it seems like I fixed it by re-rigging the character. I will however be on the lookout for the issue and I will report back with more substancial documentation of it if it happens again :)
It's very nice to know that you are still working on this though ^^ I really like it so far :)