Universal remote volume control stops working once I click it works in the setup, also the phone support is abysmal.

Our old tv went out unexpectedly, and we had to replace it. Went to Walmart and picked up a Hisense 43R6E4, hooked it up, and got it working. Then came time to program our universal remote, as one does, so we wouldn't have to use 2 remotes. I go into settings, program remote, add tv, Hisense, and the model number isn't listed, no big deal. I click model number not listed, do the programing and it works, volume up, down, mute etc., I click it worked, because it did, and when I got back out to the TV broadcast, the volume no longer worked. I switched to TV at the top of the remote, and everything else works, TV power, source, menu navigation, channel control, just not volume, even though moments before it was working no problem. So I go through all the codes that "worked" and none of them let me control the volume past the setup screen.

Let me know if any of you have a clue what's causing this, phone support sure wasn't any help. Barely understandable, ignoring my questions to read from an obvious script, and giving me no real help outside of what could be easily inferred by someone with moderate knowledge of tech. Also, the "live chat" doesn't work, the link literally is an undefined expression, that leads to nothing. You may say, "It only works when there are support agents online." Ok, cool, THEN TELL ME THAT, instead of leading me on this wild goose chase across the internet just to see that people have been complaining about it not working since like 2018. It clearly says "Billing and Account Support is open 24/7. Technical Support is open 6 AM - Midnight CT."  Not upset at the individual I called, they were doing their job, upset at the company's low respect for their customers.