Preview recognized as "created by an unidentified developer" application when open PDF files if set as a default app to open
When I set Preview as default app to open PDF files (created by Acrobat Professional), I get a popup saying "Cannot open because the file is created by an unidentified developer". I can open Preview itself, and I can open these files from Preview if I opened it first. Anyone knows why this is happening, and possible remedy?
Thank you.
My Mac Mini: 10.14.5 Mojave
Acrobat Professional: Version 8.0.0.