I have an issue on an Ai file I am working in. As it randomly changed increments to 1pt. My default as I like it, is always 0.5pt. I change it to 0.5pt and it stills moves 1pt. I open my other Ai files and they sync with whatever increment I make it to in the settings.
Why is this one file not cooperating? I've been working in this file for weeks and is setup the same as the others, nothing special.
Just like the preferences, a single AI document can become corrupt. The corruption can (also) be in some of the artwork, so you may have to recreate some.
The solution is to create a new document and move the artwork into that by copying and pasting into the same place and stacking order, Ctrl/Cmd+C in the ailing document, then Ctrl/Cmd+F or B (front or back)) in the new one, and see whether everything works.
You can work from the top or bottom of the Layers panel and start with whole Layers (if more than one), and in each Layer you can start by selecting everything (Ctrl/Cmd+A with nothing locked/hidden) and trying to move everything over in one go, and see.
Failing that you can try to divide the artwork into part, and see whether things work before the next part.
In this way you will hopefully soon have a working document with all or most of the artwork.