So far updating the agent settings to 6.2.7 with tools 10.2.5 has resolved my issue. Hopefully it remains.
In case anyone else is searching for this issue, I wanted to share my experience.
We just rolled out Horizon 7.6 with VMTools 10.3.5 on our Win7 & Win 10 pools.
We noticed that our Dell/Wyse 5040 devices running the updated ThinOS 8.6_013 code had the mouse cursor disappear when hovering over test fields.
The setting above, resolved the issue.