Blokada 6.0 (from play Store) or 5 (from the Blokada web site? If it is the latter, my suggestion would be to download again. Doing so should give you Blokada 5, v. 22q3f, which is the most recent version of 5 and is what fixed my problems with Blokada 5 on Android 8.1.
If you have downloaded from Play Store, then you actually have Blokada 6. I am afraid that i can’t help with that since i don’t use it.
Edit: one thing i dislike about the web site is there is no indication of a version update. I just checked, and sure enough, there is a newer version, v.22307, which shows in Blokada as “blokada/22.3.7”. Sorry about that. I should have checked before posting.