Images (jpg and png) uploaded in TinyMCE outcome as type text/html

We let the customor upload images in tinyMCE but they will be set to type text/html instead of type is jpg or png. This way the image is not visible in the tinyMCE editor as well as in the frontend of the shop. I assumed it would be a MIME type problem, but that's not it.

Has anyone else encountered this and do you have a solution for this?

here you will find a printscreen:

https://www.goedkopeverhuisdoos.nl/nop-test/frontend_output-console_network.png
https://www.goedkopeverhuisdoos.nl/nop-test/frontend_output-elements.png

The path of the image is as it should be, but the type is not as it should.

Hope anyone can help me out.

Could you please provide a complete list of steps to reproduce the issue?

P.S. The second link doesn't work

We have fixed the problem.

runallmanagedmodulesforallrequests is set to false and this will make the fault.