Not sure if Garmin ever fixed all the issues but here’s a thread from back in July –
Import a workout file from Xert into Garmin connect - Support - Xert Community Forum (xertonline.com)
Option A (TCX export) is a bit tedious and only works for workouts without too many steps unless Garmin has fixed that problem with a firmware update by now.
Option B (Connect IQ app) allows you to run the workout as intended (including SMART workouts) but there are reconnect sensor issues when the workout is completed and you close the Xert IQ player. That’s not an issue indoors but would be outdoors (stop and re-pair sensors). This is another Garmin problem which I don’t think is fixed.
Perhaps someone with a 530 will chime in with their recent experiences.
My 1030 sits on my trainer desk and hasn’t been used in months. I may still use it occasionally for outdoor free rides when spring weather hits, but the phone apps are much better for indoor workouts.