50ft is very long for HDMI. That one works and the other doesn't: you're at the margin of it's capability. Anything can happen.
For Blu-ray you can switch between 1080p24 and 1080p60 by turning the 1080p24 setting on and off. You can switch on 1080i60 by selecting that as an output resolution.
Same for DVD (the DVD 24p setting is optional). When sending 1080p it sends the same bandwidth as Blu-ray. HDMI video is fully expanded in resolution. DVD is a lower resolution source but when upscaled will be the same bandwidth as Blu-ray.
You could play your DVDs now by setting the player to Source Direct or 480i or 480p. It would be better to get the HDMI working properly, though.