This could easily be a function of how the layout is designed, account privilege set permissions, or the relationships on which the layout is based.
Thank you for your post.
Assuming the layout is damaged, have you tried to create a new layout with the same fields/objects? If so, does that work?
Try creating a layout based on the same table and include only one field. Are you able to create a record? If so, are you able to enter and commit data into the one field?
Any other information you can provide may be helpful.
Thank you for your help and prompt replies.
I found the problem, it was a non-functional script that was triggered on record commit & record open. It was connecting to a third-party API that wasn't responding, so it just stalled the entire record creation/modification process.