I am replying to my own question to give an update. VMware support came back to me, and had me boot the to-be-converted machine onto an older kernel, and try to v2v while running the older kernel.
As I have successfully run the converter against other 7.5 machines, this sounded promising.
I booted the 7.6 machine onto the latest 7.5 kernel instead of the original 7.6 kernel. The machine booted properly, but the conversion failed as before. The machine times out after getting to 98%, and the same error of...
FAILED: An error occurred during the conversion: 'SysCommandWrapper: Error encountered in SysCommand:
SysCommand failed to wait /usr/lib/vmware-converter/chrootAndExec.sh to terminate'
Still awaiting the response from VMware.