Custom task type not saving

I’m working on two Gantt pages, one of which uses the default task type and submits changes to the server properly. The other has a custom task type (to represent equipment locations) and does not communicate with the server when I click “Save” in the lightbox.

I am loading the data with gantt.parse(), and I’m not using the recommended DataProcessor approach.

What would prevent my custom task type from saving?

Hello,
It is hard to suggest what might be wrong as I don’t see your code.
Please add your configuration to the following snippet and make sure that the issue is reproduced there:

Then, click on the Save button and send me the link.
Or send me a ready demo with all the necessary JavaScript and CSS files so that I can reproduce the issue locally.