How do I troubleshoot Hide My Email issues with return scheduling and vendor communication on iOS 26?

I used HME for Christmas purchases and now encountering problems scheduling returns. Some vendors have no record of either address (HME or regular email address) so I cannot log-in to the vendor account. I also don't know if vendors are even receiving my emails bc I'm not receiving replies. Yes I check all folders.

I'm wasting time trying to resolve issues that normally would take just minutes to fix, INCLUDING trying to locate HME "passwords" which are stored in a completely separate area from other "passwords."

[Re-Titled by Moderator]