After upgrading our VDA to 2402 cu1 we are presented with black artifacts on launch of Horizon app.
Remove Seamless flags 0x00020804 from VDA
HKEY_LOCAL_MACHINE/System/CurrentControlSet/Control/Citrix/wfshell/TWI
Value Name: SeamlessFlags
https://support.citrix.com/s/article/CTX101644-seamless-configuration-settings?language=en_US
Non-default Seamless flags seamless flags 0x00020804 causing certain child windows to be presented incorrectly