Trying edit fillable forms

I am new to Adobe Acrobat Pro. I am testing the options to create fillable forms in Adobe. I briefly tested UPDF, which I found intuitive, but could not test more complex forms without purchasing.

I am running  a trial of Adobe Acrobat Pro.

I created a fillable form from excel. So far so, it seemed to work. Then I needed to edit and when went back into the form I could no longer see the list of fields. In addition the pdf was no fillable at all. I can alos not recreate the fillable form from scratch (it is not very complex) because I am getting anotification that @no new form field annotation were detected'.

Is it not possible to fully edit a filable form that you created?

Why has the fillable functionality stopped?

Sorry if this should be obvious. I am under some time pressure to test and decide on further purchase.