Rendering custom RenderTarget with shaders

Hello everyone, I'm one of the developers of SecurityCraft, and I have a question regarding shaders and Iris. In our mod, we have a feature where players can view another part of the world as a camera feed in a "Frame" block. The camera feed is a RenderTarget that is first used to capture the remote world view, and then rendered in the Frame's BE renderer. The code responsible for this (buried in some other code, sorry about that!) can be found here (starting at around line 113), we also use a custom core shader for this, found here. During testing with Iris and both the BSL and Complementary shaders, we've noticed that while using the shader, the frame feed does not show up. This either means that the world capturing doesn't work, which I doubt because Iris shouldn't really mess with that, or that the rendering of the RenderTarget into the world doesn't work. Since I know very little about shaders and graphical development in general, I wanted to ask in here whether someone with more expertise might be able to take a look and potentially find a solution. Maybe this is also just a problem with BSL or Complementary respectively, in that case I'll go over to their Discord servers. Feel free to ping me. Below is a comparison between Iris + no shader (the intended look) and Iris + BSL.