HDCP error on new external monitor connected to new MacBook Pro

System: 13-inch 2020 MacBook pro with Four Thunderbolt 3 ports (purchased Sept. 2020)

2GHz quad core i5 16 GB memory 2TB SSD

External monitor:" LG 24ML44B (purchased Nov. 2020)

Resolution: 1920 x 1080 (1080p FHD - Full High Definition)

UI Looks like: 1920 x 1080 @ 75Hz

Framebuffer Depth: 30-Bit Color (ARGB2101010)

Mirror: Off

Online: Yes

Rotation: Supported

Adapter Type: DVI or HDMI

Monitor and MacBook Pro are connected via an Apple USB-C Digital AV Multiport Adapter and an Insignia 4K UHD HDMI switch (3 ports)

Additional info: monitor is shared via the switch with a Raspberry Pi 400. I also have an older iPad Mini (ME277LL/A) that I occasionally connect as a 3rd monitor via the Duet app. The iPad is not compatible with Sidecar. running the Duet App consistently causes a HDCP error and so I have stopped using Duet.

PROBLEM: I have been unable to consistently play videos from the Apple TV app on the external LG monitor. Most of the time I get the HDCP message that the video cannot be played on the LG monitor because it is not HDCP compliant. However, I have on a couple of occasions gotten past this error and played video from the Apple TV app on the LG Monitor.

Things I have tried:

1) Connecting the monitor directly to the MacBook via the Apple USB-C Digital AV Multiport Adapter (bypassing HDMI switch).

2) Using different HDMI cables in different configurations.

3) Resetting the NVRAM/PRAM

4) Clearing the Apple TV app cache

5) Shutting down and rebooting

6) Shutting down, disconnecting cables, rebooting, and then reconnecting cables.

7) checking for software/firmware updates for the monitor

8) Turning off screen sharing.

9) Closing the laptop lid to force a "handshake"

10) turning on Mirroring.

Any other advice, or tips? I've search Apple Support, the web, etc, and can't find anything specific to this issue. I have gotten it to work ONCE but have been unable to recreate it.