I had a devil of a time getting Proton integrations working today.

Proton Mail often neglects to present a Yes/No/Maybe event invitation for emails that contain ICS attachments. So it is difficult to reliably accept business meeting invitations with the Proton platform, compared to Google.

I tried opening the ICS attachment on my phone. But Proton Calendar fails to appear in the OS share menu for ICS attachments.

Then I tried downloading the ICS as a file. But neither Proton Calendar nor Proton Drive appear in the OS share menu for entries in iOS/iPadOS Files.

Then I tried using the Copy and Paste functions in Files to upload the ICS file to my Proton Drive. On a separate device, I tried clicking around the Proton Calendar Web UI for an import button to upload the ICS file. But I cannot find local ICS file import options anywhere.

As a last ditch effort, I blindly copied and pasted the ICS file onto the main portion of the screen. There is NO visual indication that this website supports ICS file uploads this way. But it did work. That's way too many hoops to jump through to accept ICS invitations in Proton Mail onto my Proton Calendar.

About 90% of the event invitations in Proton Mail successfully update event data in my Proton Calendar. However, some other events silently fail to present an invitation UI in Proton Mail.

Conversely, some Webex invitations for POSIX discussions in Proton Mail are permanently displayed in Proton Calendar. No matter how many events I decline or delete, more Webex events spam my calendar in the future. I have already marked the emails that provide that ICS data as spam. But the events still come through regardless. Ironically, the very events that I have no interest in attending appear reliably on my calendar, but it's very difficult to manage ICS file invitations for the events that I do want to attend.