Arguments not saving

When I experienced the same issue, I found this thread which didn’t resolve my issue, however a different thread on a different search did.

My resolution involved that I inadvertently added an ImplementationVersion value to the workflow. The resolution was to leave that property value as blank everywhere, here is link to more details UiPath Library: Assigning an Implementation Version eliminates Arguments list on Save - #2 by GenXDo

So if you are having this problem and do have an ImplementationVersion set then look into that situation.