Simple usecase we have every day: a dev wants to pick several sub-tasks at once...

Have team members here that are constantly annoyed by the lack of this support. I can understand it in the event of different issue types that can use different screens between transitions – but even lacking the support for the same issue type is a pretty lacking feature.

I'm working with a client who really needs this feature.  They have field service techs who perform multiple service operations at a time and need a simple way to close them all, leaving the same comment on each.  They also want to be able to add the same attachment to each issue.  I know it's an edge case, but it seems like an elegant solution might be the following:

When the user drags multiple issues on a board:

• Display a screen with any fields that are common to all of the issue types.
• If screens are present for the others, have a section for each issue (collapsed by default) that, when expanded, displays the fields for that screen/issue type.

That would solve for my client's use case because they only need the comment and attachment field, which can be common to all issues.  They would never have to expand the other sections, unless there was a required field on one of them.  If that were the case, that section could be bubbled to the top and expanded by default.

They require the use of a board (instead of issue navigator) for their service techs because they want to keep it as simple as possible.  Also, they would never give bulk edit permissions to their techs because the aren't really Jira savvy and could easily cause serious damage.

They don't want to use Jira Service Desk at this time - Just Jira Software.

Just some of my thoughts...

Yes, missing this feature desperately. I could see it either ask for every single issue or bulk set the values.

Alternatively it could simply ignore the issue screen. Admins could use conditions to prevent certain transitions without showing the screen.

Quite a surprise for me, too.  I recall the ability to do this in the past.  Good thing I have bulk edit permission

Transition screens work with single issues. I'd expect the behaviour with multiple issues to set all issue fields to the values entered in the screen.