No, this got strictly nothing to do with the group tag. This is just that if you cannot select an object (with all criteria met for "Select only my objects", which also encompass objects not owned by you but you got modify rights for), then you cannot drop an object (rez it) onto it.
Anyway, this is fixed. I even reverted the bogus code by LL and made my own, much simpler code (with the same trick as for the new "Ignore click" object touch-action feature) to deal with reflection probes selection/picking. So the next v1.31.0 release will behave in the exact same way as v1.30.2, excepted for reflection probe objects (fully ignored but when the build floater is shown), and only them !