Thunderbird 86.01b snap doesn't follow link in messages

I originally installed Thunderbird 84 on Ubuntu 18.04 via the Ubuntu software manager. It was not a beta version. On December 31, 2020, I upgraded Ubuntu to 20.04 LTS. At that time there was no change in Thunderbird. Since February 1, the Ubuntu software updater has installed a couple of updates. Apparently one of those updates included 86.01beta. I don’t recall that being a choice that I could make or reject, however that is what I have now. This version doesn’t follow links in the messages. When I attempt to follow a link, I am prompted to choose an application from a blank list.
I have Chromium installed in snap and Firefox in /usr, but neither appears in the Choose Application window.

When I reported this on AskUbuntu, I was advised as follows: Advice: Thunderbird is unable to follow HTML links seems like a bug. Please report it: https://snapcraft.io/forum.