The latest release of Message+ 6.9.0 was updated on my Galaxy 10 on August 8th.  That matches up quite well with when the desktop version quit working.

Looked on my laptop, and I have the the following error/Failure in the event log:

Installation Failure: Windows failed to install the following update with error 0x80073D02: 9WZDNCRDCSNZ-VerizonWireless.VerizonMessages.

8/9/2019 10:08:34 AM - same day my cell phone verizon messages app updated.

Windows Update Agent

Failure,Installation