Knowledgebase:
Schoology: "LockDown Browser was launched with an invalid custom launch URL payload"
Posted by Respondus Support

This error is typically caused by using an ampersand (&) in the quiz title. This bug has been reported to Schoology and may be fixed in a future release of the Schoology LMS.

Removing the ampersand and replacing it with "and" will resolve the problem. In general, a best practice is to never use special characters in course or quiz titles.