Every time I use layer parenting this glitch crashes my animate cc file.

almost everytime I parent one layer to another, the mouse will get locked in grab mode and I cant select anything. adobe animate crashes soon after the glitch first happens. If there is a way to get this fixed that would be wonderful! 
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unfortunately I cant get a good image of the problem.
 

this is in Animate CC v 21.0.7
thanks for your help!