After a lot of trial and error, uninstalling, deleting certain files I’ve think I have discovered that Windows v1.0.4 of DecentSampler appears to have a bug that will not allow you to permanently change the Sample Library Location. And that could be a cause of this issue.
It is set by default as;
You should be able to set a different folder when first installing DecentSampler or change it later on in File > Preferences and it does appear to change, but it will revert back to the default. This was not an issue with v1.0.2. I’ll get in touch with Dave Hilowitz about it.