error in SP Project & Document Manager showing content of sub folders

When creating a sub folder with SP Project & Document Manager, and opening it, it shows huge blownup images of thumbnails, which are links to:

javascript:sp_cu_dialog(‘#edit_category_8’,550,130) ( edit map name)
https://www.zorgwisselgroningen.nl/werknemers-2/# ( remove map )
javascript:sp_cdm_load_project(0) ( go back )

(Already when opening the sub folder it shows a huge turning gearwheel gif)
Is there a way to reduce these images in size? Or have the plugin create text links instead of these thumbnails?

I checked the settings. I’m running WordPress 5.3.2–nl_NL and version 3.6.6. of the plugin. Any help will be appreciated.