Same is happening to me... unfortunately the laptop I'm using automatically updated and took me a while to get it running.
Just select in PRODUCT > DESTINATIONS> SHOW ALL RUN DESTINATIONS and the ROSETTA simulators will appear :)
UYFelipe
Users receive reputation points by contributing quality content to the forums.
Posts include post and replies published on the forums.
Post authors can mark replies as Accepted to indicate successful solutions.
Apple Developer Forums admins can mark replies as Apple Recommended to indicate an approved solution