Why am I getting an error message can't find app to open file trying to open ICS Caledar file with Inbox by GMail?

[AC Question]

"can't find app to open file" trying to open ICS Caledar file with Inbox by GMail

Whenever I select an ICS canlendar file in Inbox, I get the error message "can't find app to open file". If I switch back to the old gmail app, the ICS opens fine. Is this a compatibility issue with Inbox and Android 4.4.2, or a bug with Inbox.

BTW, using a Samsung Galaxy S3