Pathway to thumbnail issue in Unity/VRChat SDK

When I go to build my avatar I cannot add a thumbnail to my avatar, making it impossible to upload. I have tried to capture and upload a thumbnail, both methods result in either a white or black image that doesn’t count as a thumbnail. Once I try to publish it doesn’t work and a “pathway to the thumbnail” cannot be found, making my avatar unuploadable. If anyone knows a fix please let me know!
Thumbnail Capture Attempt
Thumbnail Capture Aftermath
Upload Failed

have you tried reloading the SDK at some point ?

Sorry my response took so long, but yes. I reloaded the skd, and I even reinstalled it through VRC Creator Companion. I just rebuilt the avatar for online testing and success! However, the thumbnail issue is still present.