WebGL and videoplayer set frame not working in Unity 2019.4.0f1

Hi all! I have a real issue with WebGL build, videoplayer and UI controls. My application has a part where the user can control a video using a slider component. Basically I'm setting frames of the videoplayer with a slider.

The video works, np. The controls script is simple, and I set slider minvalue to 0 and maxvalue to framecount of the videoplayer component. I tried debugging this in the developer console in Chrome, there is no problem either. When I release the slider, I get the slider value and set it to the videoplayer.frame. It all works as it should in the editor 100%. However, when I stop dragging the slider in "Build and run" inside Chrome it just resets my video to frame 0 and restarts the whole videoclip. Does anyone have a clue about how I could maybe work around this issue? I already tried the simple way, also tried giving the videoplayer a few (as much as 20) seconds to prepare, tried pausing video first...Nothing seems to work... I really have to make this work. Or else! Or else what? Exactly. Thanks for your attention and your time