Horizon 7.9, linked clone desktop pool.
After Recompose Gold image in the VMware Horizon Client disappears choice Remote display protocol (Microsoft RDP is offered by default).
If change the Default dispaly protocol in settings Desktop pools, then in the VMware Horizon Client will be fine for a while - there will be a choice of Protocol and the default will be PCoIP.
However, after a while the choice of Protocol disappears again.
This is a known problem with Horizon 7.9 and will get fixed in Horizon 7.10.
Quote from VMware support when troubleshooting this:
"Just to follow up with you to let you know that our back end engineering team has identified this issue and it is resolved in the 7.10 release which is scheduled for release in September."
We have encountered this same issue after a recent upgrade to Horizon 7.9. Our workaround is that when this occurs (after a recompose), via Horizon view, we enter the Catalog, then the Desktop Pools. Open up the affected pool and then select "Edit". Then select the "Desktop Pool" tab (which contains the "Display Protocol" settings). Then click "OK". This action reapplies the display protocol settings for the pool. The display options should now be available.