Thumbnail missing

[no2u]

Since upgrading from ZM 1.30 to ZM 1.34, Thumbnails aren't displaying in either my Event Lists or Frames Lists. Same issue occurs in Chrome desktop or Safari mobile browser. I've tried ZM 1.34.0, 1.34.2, and 1.34.5 from zmrepo, and running Debian 10, php 7.3.

Inspecting the page in the browser, I see that the image is supposed to come from the following URL for example, but Chrome reports HTTP error 500 if I type this URL in directly. i.e. This page isn't working:
https://localhost/zm/index.php?eid=282134&fid=snapshot&view=image&width=128&height=96

However, if I remove the "width" and "height" parameters from the URL the page is displayed correctly at full scale. i.e. This URL works:
https://localhost/zm/index.php?eid=282134&fid=snapshot&view=image

If I hover over the missing thumbnail using ZM 1.34.5, the video playback works correctly in the thumbnail area, but when I move the mouse elsewhere on the screen an error pops up in the log:
zms_e282134 15646 ERR Unable to send raw frame 4: Broken pipe zm_eventstream.cpp 791

I tried disabling auth, various thumbnail resolution settings, and php 7.3 is the only version enabled in apache.

Thank you for any suggestions.

[bbunge]

Check that Options - Web - WEB_LIST_THUMBS is checked. If it is uncheck, save, check and save.

[no2u]

Yes, WEB_LIST_THUMBS is enabled, but thank you for your suggestion. (If it wasn't enabled, I wouldn't be able to hover my mouse pointer above the missing thumbnail image area and see the video play -- the video does play when I do that)