Text replaced with gibberish after saving

I recently used Acrobat Pro to enter text in a fillable PDF form I'd received from a financial advisor -- mainly numbers. I then saved it in two places locally (my OneDrive and on a SharePoint) and sent a copy to the advisor. The next day he informed me that almost everything I'd entered was displaying as gibberish. When I checked the copies I'd saved, I saw the same thing. It had looked fine after I'd saved it, but I didn't close and reopen it before sending to verify it was fine.

(I should clarify that I've used Acrobat many times in the past few years to fill out and/or sign forms, contracts, and other documetns, and have never had this happen before.)

Two questions:

1) What caused this, and how can I avoid it happening again?

2) Can I recover the text I originally entered (for example, by downloading a font)? Or is it gone forever?