The primary problem is that we import multiple bundles of multiple products. The components have their hierarchy and descendance: Gantt and Calendar extend Scheduler, which extends Grid and all components use common classes that exist in all of them (stores, models, form fields, helpers, etc.). The imported bundles can then collide with each other when used on the same page which can lead to various problems.
This will be conclusively addressed in
5.x release so that all our products will work on one page or in one (React) application seamlessly.
Until then, you could wait until
4.2.0 when we plan to release wrappers for Scheduler (Pro) in Gantt so you would not need 3 bundles (Grid, Scheduler, Gantt) but only Gantt which would include them. Calendar will stay a separate bundle though. This could mitigate the problem but we need to test it ourselves.