Blockchain method shows as 12700 in example hashes online
Yet it says invalid on hashcat?
read this:

If you use version 1.37 (which is an older version than the beta version mentioned), it won't work.
Hey where can I find this 1.38.. thanks

I have a lot of experience with JTR's jumbo version of cracking blockchain and helped them solve problems they had.
The betas are not public and version 1.38 is not released yet. You need to be beta tester to get access to betas.
Any ETA on 1.38 release?