I am encountering many problems with HDMI working properly with 4K UHD and HDR in projector installations. These installations frequently use cables that are much longer than those found in the typical home installation. Many Category 2 high speed cables that are 15 ft or less in length work without a hitch. Applications over 15 ft are where most of the problems I find occur.
At this time many of the solutions people are trying are failing at distances greater than 15 ft. These include fiber optic cables, Redmere, HDBaseT and various HDMI cables that are rated for 18 Gbps. Some of the problems may be related to certain devices not working well together at this time, but most of the problems are associated with achieving the higher data requirements for 4K and HDR sources.
The most reliable solution I have found is to use a Blue Jeans Series-1 cable of 25 ft or less. These have been rated for these applications and have proven to work well. I would design a theater to use this length of cable or less if at all possible to avoid the complications and cost associated with longer cable runs.
Celerity detachable fiber optic has also been a reliable solution that should be upgradeable. The Celerity fiber optic solution also works out to 1000 ft.
A new solution that JVC has chosen to partner with is the Metra HDMI GA-1 (~$400) cable accelerator. This device attaches at both ends of your existing HDMI cable and can improve it’s speed up to 18 Gbps. Each end needs to be powered with a USB connection. I would consider installing this product with a Blue Jeans Series-1 cable for runs over 25 ft and up to 50 ft or with an existing high speed cable less than 50 ft in length.
JVC is one of the brands that I have had numerous problems with getting HDR to work with when using smart devices like Redmere or HDBaseT products. The fact that JVC is recommending this product in projector installations is a very good indication that it would have a high likelihood of success in your theater.
This product also has other benefits associated with it being independent of the cable itself unlike solutions like Redmere. There are reports of these smart cables failing after a few years of use. It can be difficult to pull a new cable going to a projector. If the Metra GA-1 was to fail it can be replaced without pulling a new cable. You could also return the GA-1 if the Blue Jeans cable alone meets your needs in your installation.