RF Out 4K

I have a dual-output setup for my Arris xg1v4 cable box with the HDMI output connected to my TV and the RF analog output connected to my VCR (yes i still use one). However, I've noticed that on events where i watch on the RealTime 4K channel, the RF modulator to my VCR shuts off with no signal until I unplug and plug the cable box in? Why is this and can I turn it off?