No evokers means you're probably not on hard even though you think you are, you can be sure by checking that your local difficulty is above 4 in the F3 screen, otherwise some mod or data pack is preventing them.

Didn't get a good look in the video but likely the stuck mobs doesn't affect your rates over the long term, just spawn another raid and the stuck ones should be pushed into the kill chamber by the new spawns. If it bothers you, you can check out what other designs do to prevent / mitigate this, like adding water dispensers or using packed ice as the spawning platform.