external displays receive input signals ONLY when I open a Powerpoint file and use slide show mode?

At work I use two external displays as extended monitors. Today suddenly I lost my input signals to both external displays.

Strangely, when I opened a Powerpoint file and read the slides in a slide mode, the slides were projected to the third display (which has an "in-slide" control panel to move forward and backward the slides) while the second display is considered "co-display" with the laptop monitor (as indicated by 1|2, and 3, when I tried to identify the displays).

What happens to the two external displays so that Powerpoint slide mode can project signals to the two external displays but when I close the Powerpoint file I would lose the input signals to the two external monitors.

And how can I resolve the issue of "no input signal" to the two external displays when I close Powerpoint program?

Solution 1:

I have the same problem. I'm using a new Thinkpad 15" 20MAS4EX with a lightning dock on Windows 10 Version 1809 Build 17763.615.

My experience:

1. May 2019 Receive new Thinkpad 15" and Thinkpad lightning dock, 2 4k monitors extending with 2x Mini Displayport from dock...everything working! :)

2. a. June 2019, Mini Displayport stops working. :(

3. b. Switch to HDMI and both monitors work again to extend :)

4. a. July 2019 HDMI stops working on both monitors. :(

5. b. Very sad, same thing had happened on previous Dell laptop and dock. Just use laptop by itself. :(

6. a. August 2019, launch a presentation accidentally with monitors connected via HDMI and both work. :|

7. b. Current state: As long as I launch a PowerPoint Presentation, HDMI works the 2 extended monitors. I can minimize the presentation and use the displays. ?-:)

Like the original poster, I would love to know why.

This is my state when I'm not in presentation mode. The monitors are "seen" in Display Settings, but not active or usable.

This is what happens when PowerPoint is in Presentation mode.

Solution 2:

Try this:

1. Turn on a Powerpoint presentation
2. Press F5 to start slide show
3. Restart computer (without closing the slideshow)
4. See if it works

-V-V