Even in the latest build of Vegas 421 it crashes hard when importing more than 14 or 15 clips from a Hero. It may be the 60fps. I just imported 40 clips from a JVC 4k camera as mov files (their default) and it wasn't an issue.
Windows 10 Pro build 18362
Intel Core i-9-7900x @3.30 ghz
Ram is 32 gb
Hard drives: Lots of them. 3, 1 TB SSD. One for OS and Apps. Others for media. Also DAS Raids with 16 TB of storage (2).
Video Card is NVIDIA GEFORCE GTX 1080ti 1,048,576 ram