Glitch Resolved (To an extent)
I managed to create a stable file, by splitting the assembly into the 3 smaller assemblies, and only using the fastened mate. This means the CAD model will not accurately show possible degrees of motion, but at least I now have a stable file. The glitches might have been caused with the quarter millimeter difference between the bearing races on the v-rollers (shown in the second image), and I might have mated parts to different bearing races, causing an impossibility and unstable files. But I do not feel like remaking this assembly for the 4th time, so I might just leave this “fastened mate only” version as the final version of this assembly.