We are currently investigating a similar issue with R9 295x2 GPUs, apologies for any inconvenience caused.
I will share your feedback with engineering. Please can you attach (do not copy paste) your DXDIAG report to your next response?
Please try the steps below to see if this recovers the CrossFire options.
Use DDU to remove the current amd drivers.
Turn off your system and physically remove the second GPU from the system.
Turn on your system and download and install Crimson 16.9.2.
Restart your system after installing the driver. Once Windows loads, turn off the system.
Insert the second GPU into your system and boot into Windows.
Allow Windows a minute or two to detect and automatically install the AMD driver for the second GPU. The screen should flash black a couple of times.
Restart your system and check Radeon Settings > Gaming > Global Settings to see if the CrossFire options have reappeared.