If it helps, my go-to USB-serial adapter (also Prolific) went belly up on me, and a couple of the replacements I bought (all Prolific based) had issues.

I finally bought this one:

https://www.amazon.com/gp/product/B01LXHTD3Z/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

No problems with it.