[JRTJH]

Have you considered running a spare coax cable from the bedroom TV to the main TV to troubleshoot whether it's the signal amplitude causing the problem or a wiring issue in the Wingard cable splitter/amplifier switch plate???

You "could have" (as an example) a loose connection/short center wire at the trailer cable connector input fixture and there's enough signal to power one TV, but not enough to provide a "split signal" to the second TV. That's just one possibility out of many, but I'd first rule out the Wingard system with a "temporary bypass cable" to the second TV.