I have some courses with a grid format.
Their grids contain pictures to illustrate the topics. These pictures display successfully on all common browsers, except Internet Explorer (version 11 tested).
The %server%/pluginfile.php/123456/course/section/12345/gridimage/picture.jpg pictures are being sent to browsers in the PNG format. Most browsers work out they should ignore the filename but IE doesn't.
Other JPGs in the course work fine.
I'm using Moodle 3.4 on Apache.
Is there any particular way the server (especially PHP) might be set up that would be having this effect?
Yes, despite the file extension, the JPG grid format topic pictures on my Moodle instance are being rendered as PNGs (but not the other JPGs in the course). If this was happening for everyone, I imagine nearly 100% of users would be upset. So I expect the issue is specific to the way my server is set up.