Sice 15.4 all of our H.264 exports will be corrupt during the last 2 seconds, when saved to storage using the AFP protocol. It seems the files are not being properly finished at the final stages.. ProRes exports are ok.
MacOS 10.14.6. Also the same issues on machines using BigSur.
Specs below, although we have the same issue on other systems, iMac i9 + 2013 MacPro