When Edge is started using 'runas another user', the identity of that other user is not used when interacting with other resources. Rather the workstation logged on user continues to be be used instead.
IE is still the only browser that supports this well. Now it seems we have regressed into chrome behaviors, since it didn't work properly there either.
Its still the case that I work with 3 different identities with different tiered access rights for regular, admin, global admin. Is that not considered best practice anymore?