ehm and why you think is fault of pocket4k the fact that you use a lens with an adapter and stabilization not work?
seriously, if you use a native m4/3 lenses and not work stabilization, is a camera fault like i read with first series of 12-35 2.8 lumix, but if you use an adapter that translate camera commands... you cannot give directly fault to the camera.
i used many adapters with many cameras, low and high end, and never i found linear support from lenses' features to cameras.
gh5 with 3 different adapter to same lenses, only metabone give me fast autofocus and dual stabilization (camera and lenses), other give me problems.
sony alpha a7r, a7s2, same lenses 2 different adapter, only one give me stabilization, and no one give me autofocus fast, continuosly searching, with the same lenses that work fine on gh5.
canon 1d these lenses work fine on stabilization and autofocus.
lenses test = fine
lenses with adapter on one camera = fine with only one adapter
different adapter with different cameras = someone work someone not...
all these words to tell you... could be an incompatibility between vitrox and pocket 4k, not be the first or the last.
my sacker falcon lite (chinese alternative a bit low cost to metabone from ef to mount E, only 250$) give me different support function between A7r, A7s2, A6500, same lenses and adapter, on 6300 no work autofocus, stabilization, iris...