X-T5 stabilisation with Tamron 18-300mm F/3.5-6.3 lens

[Uncleants]

I have just bought a Tamron 18-300mm F/3.5-6.3 Di III-A VC VXD B061 lens to use alongside my Fujifilm 16-80mm F4 Kit Lens.

I am finding that while image stabilisation seems to be similar for still images at equivalent focal lengths this is not the case when recording movies, where the Tamron lens shows noticeable 'shake' compared to the Fujifilm lens at equivalent focal lengths. I have set image stabilisation on the X-T5 to IBIS/OIS. I am on latest X-T5 firmware 2.03.

I have notified Tamron but meanwhile would appreciate any thoughts, advice or experiences on image stabilisation using non-Fujifilm lenses with X-T5.

By the way, I am very happy with image quality of the Tamron lens from the tests I have done so far. It's not professional quality of course, but neither am I and it saves carrying multiple lenses around when out and about.