Problem: Error encountered when WMTS layer is added to Webmap and accessed in Field Map in ArcGIS Enterprise v10.9.1

Steps to reproduce in ArcGIS Portal v10.9.1
- Open a new webmap and add WMTS layer
- Save the Webmap
- Open ArcGIS FieldMap from apps tray

- Select the webmap created in step#2 to configure
- Select ‘Content’

- Below error appears:

Additional note:
- The WMTS layer appears fine in Webmap without any error. I am the admin so access is not an issue
- This error did not appear in v10.9 and appeared only after upgrading portal to v10.9.1
- WMTS URL to reproduce(pls note this one I found on internet. cannot share the one we used). This seems to be irrespective of which WMTS sample service we use
https://wmts.geo.admin.ch/EPSG/2056/1.0.0/WMTSCapabilities.xml