So I've seen similar questions to this one, but they dealt with P&T addons Matrix & Assets. The problem I am experiencing is with EE Native Grid & File fields when they are placed inside of a Low Variable.
The file is uploaded correctly, it's not a permissions issue. I can see the file in the file manager and use it in other fields on the site.
My Low Variable is a Grid type, and it's got a column that takes a file upload. When I select the file, it shows the thumbnail, but as soon as I click 'save changes', it is gone.
When I logged the DB queries that ran when saving the field, it showed that the file field is getting set to NULL.
I'm running EE 2.7.3 and LV 2.4.0