If you used FQDN instead of IP Address to work in your VDI environment, please check again the DNS settings of each zero client, they must resolve each naming convention related to the Horizon connection servers in every step to login the desktop. (We had similar problem like this, So I don't think it's related to the device vendor or firmware version)
Also as your Zero Client device have a log repository, you must check it first to find any related problem then check the VDI Servers like connection and composer serversPlease mark my comment as the Correct Answer if this solution resolved your problem
Thank you for your reply and suggestion.
All the zero client can resolve the FQDN. As I have mentioned before. One person can't get the VDI menu on a specific machine but a different person can on that same machine, to make matter worse, the same person having trouble with getting to the VDI menu, they can get on with another machine right beside the problem machine.