Not sure if this helps, but some of our users were complaining about mouse cursor symbol not getting updated as we enter or exit an application window. This started happening after we upgraded from Horizon 7.9 to Horizon 7.12. We tried several things including updating and optimising the image and changing client firmware, but nothing helped. Now we moved to Horizon 2103 (8.2) and users have reported that they don't see the issue any longer.
I think its worth building a small test environment using 2103 and see if this is fixed.
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