Change Undo limit in Indesign (18.1 x64)

Hi @neilm27298524:

This is not a change in the new version of InDesign. Undo is limited only by the amount of RAM you have installed. Most users can choose undo hundreds of times.

If necessary, you can cancel a lengthy operation before it’s completed, undo recent changes, or revert to a previously saved version. You can undo or redo up to several hundred of the most recent actions (the amount is limited by the amount of RAM available and the kinds of actions you performed). The series of actions is discarded when you choose the Save As command, close a document, or when you exit from the program.

—https://helpx.adobe.com/indesign/using/recovery-undo.html

My best guess is that this is an issue with corrupt preferences. Take a look at this post and work through it and let us know if that takes care of it for you.

https://www.rockymountaintraining.com/adobe-indesign-rebuilding-preferences-cache/

~Barb.