I'm having some trouble with the PSBT workflow on testnet for my first time. I was able to create 2 PSBTs and I can successfully decode them both using decodepsbt but when I try to run joinpsbts I am getting JSON parsing errors.

Help tells me;
joinpsbts ["psbt",...]
Examples:
> bitcoin-cli joinpsbts "psbt"


I have 2 PSBTs, I ran the command, but I must be messing something up...

I have 2 outputs that are basically;
"psbt": "myPSBT1",

and

"psbt": "myPSBT2",
  "complete": true

When I try
> bitcoin-cli joinpsbts "myPSBT1","myPSBT1"

I get;
Error: Error parsing JSON:myPSBT1

Not sure what I am doing wrong, but 1st time, so I'm sure some user error...

EDIT: For clarity, I ran createpsbt and then walletprocesspsbt separately on 2 unique PSBTs. Now I'm having trouble running joinpsbts and/or combinepsbt successfully. Both give the same JSON errors.

Further edit, I used my same 2 original transactions and instead of createpbst, I used walletcreatefundedpsbt and then tried to joinpsbts on those outputs, and no luck either.