Allow to group a single Intertwine object
A way to workaround the bug with the self-expanding Intertwines on effect application (https://illustrator.uservoice.com/forums/601447/suggestions/45845533) would be to group them and apply an effect to this 'protection container'...
But alas, Ai won’t allow that, and grouping an Intertwine object does nothing.
I suspect Illustrator treats it as a group, onle a 'magic' one, and normal group restrictions, such as 'Thou shalt not group a single group' are applied to it.
Why then we can’t ungroup an Intertwine... anyway, this one should not be applied, even if you fix the self-expanding.
If one needs to group an intertwine, to apply a shadow to it or anything like this, there are too options for now:
1. Create a dummy object, like a rectangle, group it with the intertwine, then delete the box only
2. Use the Group Anyway script — https://onthehead.com/ais/group003