* Which 3050? (Micro Form Factor, Small Form Factor, Mini Tower)
* Are the 3050s using the same monitor models?
* Are the 3050s using the same operating system?
* Are the monitors connected to the 3050 onboard DP out port? Or are they connected to added discrete video cards DP out port?
* What about when using the 3050 onboard HDMI out port? Do they have the issue?

* Which 3050? Small Form Factor

* Are the 3050s using the same monitor models? P2217

* Are the 3050s using the same operating system? Windows 10

* Are the monitors connected to the 3050 onboard DP out port? On board DP port

* What about when using the 3050 onboard HDMI out port? Do they have the issue?  I have not tried the onboard HDMI because I do not have and HDMI cable to try.

Reinstall our Intel HD Graphics driver, reboot, and retest.

I would also purchase an HDMI to HDMI cable and test.

I can't do that.  I have 7 of the same optiplex 3050 and all in one stand that the P2217 monitor attaches to.  I just can't move these computers around and try a different monitor.  

I would test those monitors on a different computer model and see if the issue follows the monitors.

I tried your suggestion and it didn't fix the issue.  When using the HDMI cable and opening up an excel document it causes the screen to flash constantly.  The only was to resolve it is to reboot the system.

Then we cannot be sure if the fault lies with the monitors or the 3050s.

I am having the same issue with two 5050s and two P2217 monitors, DP connected. All equipment is around 3 months old and the issue is happening on both systems in a totally reproductive manner, eg: opening an excel workbook (among other things). Disabling the Intel HD 630 GPU and re-enabling "fixes" the signal loss (able to do this because I am logged in remotely). At this point I am assuming it is software related as both systems started having the same issue within a few days of the first instance happening.

Have reinstalled/updated the GPU drivers to no effect

Uninstalled and let the GPU roll back (uninstall, check delete files, reboot) to 21.20.16.4627 (3/9/2017) and it seems to be stable on both systems. Asked that the client call me back if they run into it again and will update this if the issue occurs again.

Edit: It worked until Win10 automatically installed the latest drivers for the GPU. Turning off automatic driver installation to see if it is stable with the rolled back version. To turn off auto driver install with Win10 go to Control Panel > System > Advanced System Settings (near left) > Hardware tab > Device Installation Settings > Check No > Save changes. This may cause issues in the future so use at your own risk.

someone suggested to disable the intel HD Graphics 630 video card and by doing this, it has solved the issue.  I will need to find an older driver for this card.