Ah, thanks for looking into that!
A 1mm transition seems to be enough to avoid the problem.
Note that the "Show Object Open Boundaries" checkbox in Preferences does not save, so even experienced users will generate open boundaries without knowing it. By then, sadly, it may be too late to fix easily.
I'm trying to determine what the best way to notify the user about this new "feature".
1) Perhaps add a note below the Accept/Cancel buttons: "Open boundaries will be generated as not enough transition was specified."
2) Show the open boundaries in blue in the preview (even if the Show Open Boundaries checkmark is not checked).
3) Default to a 1mm transition (along with at least one of the other notifications)
4) Or maybe a checkmark in preferences "Never generate open boundaries when remeshing".
Edit: The more I think about it - I really think that no function should generate defects when using the default options.
BTW, I always save very very frequently when using the Bridge function - that crashes a lot!