I keep having the issue I reported originally. SORTABLE was a red herring: it does not help.
Weirdly and very unfortunately, it disappears when the same data is reloaded from rdb. I.e. the filtering does not work, then I restart redis without any data changes and the same FT.SEARCH query works as expected.
Attaching the rdb, but it's probably pointless. Just in case it gives you some hints on the possible cause of the issue. Unfortunately I can't send you my whole codebase and I still could not reproduce it with a simpler code snippet.
This search returned all 10 records before the redis restart (as if searching with "*"), but returns only 6 after the restart, which is correct.
"FT.SEARCH" "/h/t/idx" "@time_QUEUED:[-inf 1583932226.83]" "SORTBY" "time_QUEUED" "DESC" "LIMIT" "0" "26" "RETURN" 1 "time_QUEUED"
I will look for a workaround for now (maybe converting the time to an integer field assuming this helps?), but will keep you posted if I find a better way to reproduce.