I just experienced the same problem with Java 1.14 version. And possibly also 1.14.1 - see below.
But it won't help to give myself a new bad_omen for starting a new raid. I went outside the village, gave me the bad omen and returned then to the village: No new raid startet but the aktual broken raid with the wrong counting about one remaining Mob is still active.
After I changed from 1.14 to 1.14.1 there spawned a new loneley illager boss. I killed him the raid ends and I got no reward. Strange.
Delcour Libertus
I just experienced the same problem with Java 1.14 version. And possibly also 1.14.1 - see below.
But it won't help to give myself a new bad_omen for starting a new raid. I went outside the village, gave me the bad omen and returned then to the village: No new raid startet but the aktual broken raid with the wrong counting about one remaining Mob is still active.
After I changed from 1.14 to 1.14.1 there spawned a new loneley illager boss. I killed him the raid ends and I got no reward. Strange.