Which error message did you get? Have you checked to see if the changes went through? I’ve noticed in the few times I’ve bulk edited observations that the changes actually did go through despite getting an error message.
You might also try this method: https://forum.inaturalist.org/t/unable-to-batch-edit-over-50-pages/5530/2?u=bouteloua
(That Batch Edit tool is pretty old, so there are definitely some issues with it.)