90% sure i have subluxed peroneal. 6 months since injury and pops with every movement. original mri didn't show issues with it. will new mri show it?

Unlikely: Subluxating peroneal tendons is a dynamic problem that often requires a provocative movement of the ankle to cause the subluxation to occur. An MRI, on the other hand, is most often done as a static image without any motion to provide clarity to the images, so the dynamic problem is not visualized. A thorough exam or dynamic ultrasound can often cinch the diagnosis