I've been using custom result sources at the site collection level in the modern experience, and up until recently they have been working fine. According to the documentation at https://docs.microsoft.com/en-us/sharepoint/manage-result-sources and https://docs.microsoft.com/en-us/sharepoint/differences-classic-modern-search the modern experience is supposed to use the default source but this is not the behaviour I am seeing.
It seems things are moving to the new experience, and I have tried to edit the out of the box verticals at the Site level. Doc at https://docs.microsoft.com/en-us/microsoftsearch/manage-verticals advises they should be able to be renamed, disabled or have a query added. I cannot do any of these - am I missing something with this?
I've had tickets open for weeks with MS support and have gotten nowhere. Has anyone else come across this issue? Any workarounds that don't involve deploying custom app packages to the tenant?