Backoffice Product Thumbnail doesn't work with PrettyURL property

[rdsa]

I'm on Hybris 6.7 and after enabling prettyURLs (media.legacy.prettyURL=true) the product thumbnail images in backoffice (the ones in the product list) stop working. By inspecting the page I noticed that the url is in the following format:

/backoffice/backoffice/medias/sys_master/images/images/h65/hcb/file.jpg

if I manually change that to:

/backoffice/medias/sys_master/images/images/h65/hcb/file.jpg

it works.

If prettyURL is disabled the path is in the following format:

/backoffice/backoffice/medias/000000000000013049-02.jpeg-96Wx96H?context=bWF...

and it works

manually changing that to:

/backoffice/medias/000000000000013049-02.jpeg-96Wx96H?context=bWF...

also works

If i open the product media (even with prettyURL enabled) it works, so the problem is only with the backoffice thumbnails...

Any ideas on how I can solve this?