Automatic HTTS redirection not working reliably in Firefox

[eomanis]

I am using Firefox and I have the checkbox "Always try HTTPS instead of blocking" checked.

After starting Firefox and e.g. pasting an http://... URL into the address bar, it works the first few times and I am redirected to the appropriate https://... URL.

However, shortly afterwards, this stops working.
After pasting the http://... URL and pressing enter, nothing happens.
I have to insert the missing "s" after "http" myself to reach the site(s) I want.

This behavior also applies to http://... links on sites I am browsing.
First it works a few times, then either nothing happens on click, or when I choose "Open link in a new tab" I only get a "New Tab" tab with the http://... link target in the address bar and an empty site below it.

In both cases the sites I am trying to access show up in the "Recently blocked" list, so yes, they appear to have been blocked (instead of redirected to HTTPS).

I only discovered this otherwise awesome Addon today, so I unfortunately cannot tell whether HTTPS redirection was working in the past or with an older version of Firefox than 44.0.1.