I am currently using Firefox 55.0.3 64-bit.
With it, uBo 1.13.8 works as expected.
When I upgraded to the new WebExtensions version 1.14.8, an issue arose.
Every time I go to uBo settings, it says I need to update the lists. So I will update them, and everything looks good. But once I close the browser, and reopen it, uBo once again indicates that I need to update the lists.
I have even tried purging the lists before updating them, but that does not help.
I do have Firefox set to clear all caches when it closes.
Is this a known issue?