Fillable pdfs returned by email are blank

I have created numerous fillable forms in Adobe Acrobat Pro 2017 and am having random issues with the forms being emailed back to me completely blank. Nothing appears when I click in the fields or when printed. I've tested the forms with both Mac and PC users, some are fine, others are blank.

I use an existing form created in Word, save it as a pdf, convert to a form in Acrobat using "Prepare Form" in the tools, then save using the following steps: File > Save as other > Reader Extended PDF > Enable More Tools

I've searched for solutions but all the Q&A's I've found are 1-5 years old and not solving my problem. I'm not sure if the issue is on my end or the user's. I'm considering adding instructions on how to use the form as I suspect some folks are filling it out in preview mode, then saving, which of course will not save the entered information. But that's just a guess. Any suggestions for me or that I can provide to folks using the form would be much appreciated.

Thanks much!

Linda