I have completed this challenge three times in two different DEs and am still coming up with the same errors:

Challenge Not yet complete... here's what's wrong: 
There was an unexpected error while verifying this challenge. Usually this is due to some pre-existing configuration or code in the challenge Org. We recommend using a new Developer Edition (DE) to check this challenge. If you're using a new DE and seeing this error, please post to the developer forums and reference error id: ROPCLGEL

Challenge Not yet complete... here's what's wrong: 
There was an unexpected error while verifying this challenge. Usually this is due to some pre-existing configuration or code in the challenge Org. We recommend using a new Developer Edition (DE) to check this challenge. If you're using a new DE and seeing this error, please post to the developer forums and reference error id: BQWUKSNU



I really don't know where to go next, any help is appreciated; Thanks!
 

I am receiving this error message:
Step Not yet complete... here's what's wrong: 
An update to a Battle Station record with Weapon Status of 'Fully Operational' failed to post a Chatter message to the record. Make sure that the process is configured correctly and that it is activated. 
Note: you may run into errors if you've skipped previous steps.

The Validation rule is correct, the "Project Status' field update occurs correctly, the post is made to the chatter feed of the record (mine and the SF record that is used to verify the step) - and yet I get the error.
How should I troubleshoot this?
 

I am receiving this error message:
Step Not yet complete... here's what's wrong: 
An update to a Battle Station record with Weapon Status of 'Fully Operational' failed to post a Chatter message to the record. Make sure that the process is configured correctly and that it is activated. 
Note: you may run into errors if you've skipped previous steps.

The Validation rule is correct, the "Project Status' field update occurs correctly, the post is made to the chatter feed of the record (mine and the SF record that is used to verify the step) - and yet I get the error.
How should I troubleshoot this?
 

Battle Station Trailhead -Step 4:Ad business logic
"Step Not yet complete... here's what's wrong: 
The validation rule does not appear to have the correct error formula. Make sure Exhaust Port Inspectors have > 150% utilization' 
Note: you may run into errors if you've skipped previous steps"