Unity can't generate normals for blendshapes

Hi, I’m having some trouble with unity and I was hoping some more experienced users could shed some light on my situation, see I’ve created various blendshapes in blender for use on a character model using a blender plugin called “Cats”, I don’t believe that the plugin is the problem as I can create blendshapes normally and still get this issue but I thought I’d include as much as I can to get a definite answer. The problem is none of the blendshapes seem to actually work at all, when I move the slider in unity to increase or decrease them nothing happens. I checked the console and there’s a warning telling me about the blendshapes but I don’t have enough experience to understand what this is telling me, here is said warning:7535369--930563--upload_2021-9-30_22-14-8.png

The warning is much larger but its just telling me that all 24 of the blendshapes are broken, I’ve never experienced this issue before, does anybody know what to do here

I know I made this post less than 10 minutes ago but I just fixed the problem by joining the problematic mesh to a brand new one, I don’t know why that fixed it but it’s fixed now

can you explain it a bit more on how you fixed it? (Got a lot of those warnings while upgrading from LTS 2019 to LTS 2020)