I am going to order the Samsung T5 500gb drive. However, I am trying to use my current Samsung 840 EVO 500gb drive and I keep getting an error when my Insta360 Pro is formatting that drive. It says "formatted with fragments left over, please replace drive". I can read and format this drive without any problems on my PC after removing it from my Insta360 Pro. I have updated the firmware on the SSD drive to be the latest. I also removed all partitions and then created just the one exfat partition and ran the format option again. I still got the same message. I later realized that I can still use this drive even though the format error message was received. I unplugged the USB drive from the I360 pro and reattached it. The SSD drive passed the speed test and it is recording fine (using real time stitching at 100mbs data rate).
I think there might be some issues with the I360 Pro firmware on formatting. The Samsung 840 EVO is well within specifications and appears to be working fine. I will test later with 8k recording and see how that does.