When writing texts in short text fields (slugs) it doesn't stick


We use the short text fields for URLs and IDs (for mapping) and when trying to change whatever generated in those it doesn’t stick. It just gets back to with was pregenerated. Today I also noticed that I can enter the text in caps and it works but it’s not consequent to how we set it up. Any ideas of what could be the reason for this problem that occur recently (before it worked with no problems)?