It seems that the issue you're experiencing with DDM is a bug in the software. You can try updating to the latest version of DDM, as this may resolve the issue. You can download the latest version of DDM from the Dell website. If updating DDM does not resolve the issue, you may need to contact Dell support for further assistance. They may be able to provide a solution or a workaround for the bug. In the meantime, you can try using a different software to manage your windows, such as Windows Snap Assist or DisplayFusion. These programs allow you to easily arrange your windows on your monitor and resize them as needed.
This is on version 2.0.0.138 and 2.0.0.135. Ideally, DDM would identify windows that aren't resizable by the user and then not show the easy arrange layouts on the screen. One way to reproduce is to close a document that has unsaved changes and move the dialog box to an easy arrange tile.
DDM 2.0, easy arrange resizes windows that have fixed sizes