sorry I haven't been able to look deep into this yet. Probably will get to it tomorrow.
It seems like this is happening only when importing via share.folivora.ai, is that possible?
Could you try to attach your JSON export directly here? (share.folivora.ai does some transformations etc. maybe there is currently a bug that prevents the activation groups to work there).
It's working correctly when importing it like this! So it's an issue with my share service which I'll fix soon.
For now you can just drag it here and attach it like this (to reduce size you can check the "compress" option while exporting: