Unable to zoom in and out of in the display of a model in erwin Data Modeler

Description

Zoom functionality is not working on a model's Diagrams. This affects both Zoom In and Zoom Out with <ctrl+mouse> scroll wheel and zoom bar in bottom right of screen.  How to fix that?

Solution:

The cause of this issue is most likely due to model corruption. Cleaning the model will usually resolve the issue. There are two ways to go about this:

1.  Save as XML round trip
In erwin Data Modeler, save the model(s) as standard XML.  Open the XML file to form a new model.  

2.  Complete Compare with blank model.
Please see this article that tells how to use this method.
https://support.erwin.com/hc/en-us/articles/233414427-How-to-use-Complete-Compare-to-clean-problematic-models-

3.  In some rare cases, another possibility is that the application may not be working as expected due to some parameters somehow not set correctly.  To remedy that you will need to rename the existing node in the registry at the following location:

\\HKEY_CURRENT_USER\Software\erwin\Data Modeler\9.8.

Rename this to HKEY_CURRENT_USER\Software\erwin\Data Modeler\9.8_old1

Once erwin DM is launched again it will be recreated with the default parameters.  It will lose the a few pointers, e.g. existing connection to database / Mart and Recent File locations, but it will work as a newly installed application.