Hashcat and Vast.ai
Hi there! I trying to solve a veracrypt hash too, also on Vast.AI.

My tips.

use -o text.txt < this will save the output to hashcat folder
use session ... always name your long sessions, so you can resume it.
--session test
then you can restore it with hashcat --restore test

I am using dizcza/docker-hashcat:cuda image. It always works. If it's not working then the server is misconfigured or the GPU is too old. (NVIDIA)

i am not using hashcat command, but i cd into hashcat folder and then use ./hashcat. Try this and see if the output file is still missing.

The hash is you trying to solve is:

13733 | VeraCrypt Whirlpool + XTS 1536 bit (legacy) 

Which indeed SLOW. If you are sure you used 1536 bit XTS then use 1536 otherwise just use 512 for faster computation.

Don't forget about PIM (If you used). 

If your password is longer than 4 characters forget bruteforce. With this hash mode you can only do dictionary attack, and very tailored dictionary attacks. 

Also because of hashcat is embarrassingly parallel you need to use at least 50 000 words or 100 000 words. 250 000 is optimal.

My GPU recommendations on Vast.AI

If you can afford: RTX4090, or multiple RTX4090
Multiple RTX3080s for example 8x
Multiple A5000.

For Whirlpool i recommend rtx4090.