I am not sure, but this post here…
https://www.wix.com/velo/forum/community-discussion/wix-storage-checkboxgroup/p-1/dl-5fcc17364ce20b002d0ffbdf-5fcc15f3a032ca0034d80c97-1
Could perhaps help you (attention it’s a very big post, with lot of pages). Read all of them, perhaps you will look onto CheckBoxes / CheckBoxGroups from another view after reading all that content.