Thanks Roy, that is true, but I think I can improve the logic. It would be easier to understand / use if the page loaded first, even if only with a simple “Run” option. Currently it runs immediately you select the tool. So I’m happy to accept this as a bug.
Sorry, I should have checked before answering. It is not possible (without writing a completely new batch update system) to change this. All the tools are the same. They check for any records that need fixing immediately you select the tool. then give you the choice of just fixing that one, or fixing all in one go (subject to memory limits on your server).
It actually takes longer to do this if there are no issues, as it has to check every record to get to that answer. Otherwise it stops the instant it finds the first correction needed.
To help a little I have highlighted the note about this at the top of the batch update page: