Hmm, are you using version 'Beta 1.9.5' of the plugin? I believe I added 'cell' in this version. ('cell' has the value of the 'Cell Size' set in the plugin parameters)
Viewing post in Grid Inventory for RPG Maker MV comments
I copied the plugin itself from the demo to the base game and that solves the problem. I used the version I downloaded after I bought it (a bit a go) but it said no new updates in 24 days or something, so I assumed I was good.
Anyway, great plugin. Is there a way I can resize the player inventory windows? I want an inventory like System Shock 2 (3 rows 10 columns, centered at top of screen).
In the current version it is not possible to move the player inventory or resize it. This was done in order to make it consistent between different scenes, and make the equip windows work for an arbitrary number of actors. You can however set it to only have 3 rows with 10 columns.
I'll try to think about a way to make it possible to customize the location and size without losing desired functionality in a future version.