No persistent cache when using admin-ajax.php

My site is using a few calls through the wordpress ajax system through admin-ajax.php.

The functions i use are in a seperate call ajax_functions.php.

When i test the object caching (wp_cache_get and wp_cache_set) in a normal page template, all is working fine, but for some reason the data is always empty when using the same system in my ajax calls through ajax_functions.php.

Is this a wordpress thing or does somebody have any idea why this is the case?

I use object caching, enabled in the module.

Thanks in advance.

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