Assets not found on a specific install

Description

I have uploaded a fully working project to a hosting package on which I do not have access to the root folder (above the public folder). Unfortunately I cannot change this as the client wishes to use this hosting.

I have adjusted all the settings to reflect the fact that Craft is in the same folder as the index.php-file and got everything working as expected, except for the images. On the front-end, some images give a 500 server error (index.php?p=actions/assets/generate-transform&transformId=8) for the transform action. However, no transform should be done anymore since all transforms have already been made locally/on the staging.

When I go to the control panel's utilities and run the "Update asset indexes"-command, it says it misses a whole list of images. However, when I check the directory these images are there.

I then tried to upload these images again, via the "Assets" menu tab. Upon uploading, Craft tells me they already exist (strangely it does find them now), and I choose to overwrite them. When I clear all caches after this and run the "Update asset indexes"-command again, Craft still can't find these images.

On the front-end the result remains the same, most images do not show and a lot of 500's on transform url's in the console log.

Steps to reproduce

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Additional info

• Craft version: Craft Pro 3.0.36
• PHP version: 7.2.14
• Database driver & version: MySQL 5.5.5
• Image driver & version: GD 7.2.14