Our open source authoring tool acts as an LTI 1.3 tool provider and is capable of producing Thin Common Cartridge export files (with LTI links). Here's a sample Thin Common Cartridge 1.1 file with LTI links produced by our platform: https://drive.google.com/file/d/1TK0fQu698xnqT6w_TeLzIQthsjnN1JbF/view?usp=sharing
When our tool is configured/registered as an LTI provider with Moodle as the platform, we are able to launch LTI links and pass grades, etc. as desired. However, when we import the Thin Common Cartridge (using Moodle's 'restore' feature), the LTI links do not open as expected in Moodle upon initial launch. Instead the viewer sees an "Error: Unknown export format" message.
In order for the link to work properly, a course admin must turn editing on, and edit the settings for the external LTI link in question. At that point, Moodle runs its detection loop and finds the tool configuration which applies to the LTI launch URL for the activity (it is only at this point that the green check mark and 'using Pressbooks Integrations' message seen in the attached screenshot appears.
Once I save and display (without making any edits or changes), the LTI link then launches as expected using the already configured 'Pressbooks Integrations' LTI 1.3 tool.
See this brief video for a 1 minute demonstration of the issue: https://youtu.be/5qWmKyG6XFw
What we think should happen is that the tool URL should be parsed and checked against existing configurations at the time of import/creation, so that the links work immediately after restore, without additional user action required.