Image uploader preview not working with multisite on 5.6

[slewis1000]

Hello,
Since upgrading to 5.6 I can't upload and set images. Which is a big issue on my main site. The images seem to upload ok (and appear in the wp-content/uploads folder), but the preview never loads, so I can't use them or set them as a featured image.
It seems it might be linked to the multisite > network settings > site upload space.
I've tested this with a clean install, any theme. PHP 7.3.17, Mysql 8.0, Apache 2.4.46
For 5.5.3, I installed, changed to a multisite, toggle the 'site upload space' settings and uploading and setting images works fine. When I upgrade to 5.6, it then stops working.
When I've done a clean 5.6 install, then change to multisite, it works until I toggle the 'site upload space' it then stops the image uploader working, with whatever settings I have in.
Not sure if there's a way around it? eg putting something in the htaccess file.
I also saw this file has been updated wp-admin/async-upload.php, which when I inspected the code looks like it doesn't always load.
thanks,
Simon

[slewis1000]

5.5 image uploader working fine

[slewis1000]

5.6 image uploader stops working

[slewis1000]

5.6 network settings

[slewis1000]

5.6 network settings

[slewis1000]

It's now working ok. No idea what changed. I hadn't changed anything on my live site, and just started working a few days after I raised this ticket. It started working on all my test sites again too.

[desrosj]

Glad you were able to get this working, @slewis1000! In the future, it's best to start in the ​WordPress.org Support Forums before heading here unless you are able to identify that the issue can be consistently reproduced with a fresh install.