New LG Computer Monitor, OSSC Line 2X only, Am I SOL?

[Arcade-Projects]

I apologize, but I'm rather unfamiliar with OSSC. I've tried doing my homework via videogameperfection and shmups.org, but I just end up even more confused. I sold my Framemeister a few years back after picking up a couple 800 line PVMs for rather cheap. Before moving to Japan I decided to give OSSC a go. On my 60" 1080p Sony Bravia only Line 2X worked when trying out my Saturn. If I tried 3x, 4x, or 5x I simply got a message on the OSSC screen that read "unsupported". I read that people were having a lot better luck with 4K displays. Fast forward to now.

lg.com/us/monitors/lg-24UD58-B-4k-uhd-led-monitor (this is the monitor I bought, only the Japanese market version)

I have a Dreamcast hooked up to the OSSC via Kuro VGA box. On the RGBHV input everything looks fine, but all I can do is passthrough or Line 2X. When going to the output menu under 480p/576p processing those are my only two options. Is this the reason for when I hit "TV/AV" and then 3, 4, or 5 on the remote than I am getting the unsupported message?

What I'm confused about is this, if the Dreamcast is powered off the OSSC will still display the gray picture. If I try to go to 3, 4, or 5x here I still get the unsupported message.

My question is this: Is the OSSC telling me that my monitor straight up won't accept 3, 4, or 5X modes, or do I need to be using a different source for it to work. For example do I need to be using a Saturn running SCART into it for it to work. The fact that it says "unsupported" when no game console is even on makes me think that my monitor just straight up won't do it.

Very unfortunate if all it does is 2X. Returning things because you didn't like it in Japan really isn't a thing. I can return this monitor if its broken, but all I can do is exchange it for the same one. It still looks good, but the whole point of me buying a 4K display was to hopefully get 4X or 5X to work. I know theres a long list of recommended monitors on shmups.org that work with all modes; however, none of these were available for purchase in Japan.

At the moment I have no other consoles to test. Everything is in storage back in the states. My wife still has her PS1 at her parents house here, but I'll need to pick up a SCART cable for it (probably my quickest and cheapest option to test another source).

Any help would be much appreciated, even if it's just a confirmation that I'm shit out of luck on this monitor doing anything more than 2X. I can take any pictures or videos as needed. Thank you guys in advance.

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