Dependency arrows not shown

For quite some time we used this extension to visualize a timeline and dependencies between work items. But now the dependency arrows are not shown for most of the work items. Only a few arrows are shown here and there, but not nearly all. Is it a bug in the extension? I'm not sure if the change is due to the new Azure DevOps Boards Ux Modernization. I didn't use it until it was forced to, which was quite recently.
Edit: This seems not to be related to new Azure DevOps Boards Ux Modernization.