So I have been dealing with this issue for over 6 months.
One day pdfs preview in outlook suddenly stopped working; coming up with error "This file cannot be previewed because there is no previewer installed for it."
I have uninstalled outlook and adobe, reinstalled both (multiple times), updated from windows 10 to windows 11, reinstalled drivers, both outlook and adobe are 64 bit. Attachment handling is on and the pdf viewer selected. I have checked windows registry settings, windows firewall ... basically everything google would give me.
Power toys is not installed so that's not the problem either.