What is wrong with my Javascript ISOString date?

[Dave Grammas]

I am using the Jira REST API to create an issue worklog. I receive an error response even though my date seemingly matches the format mentioned in the error.

Error received:

Date string in payload:

I read in similar posts that including offset fixed this so I've also sent the following payload, but received the same error. Here is the payload with the offset:

Any help is greatly appreciated.