I'm having display (CSS) issues with your form on admin page for category taxonomy.
I narrowed it down to poor css in the plugin itself:
The element with class rwmb-tab-panel has an inline style for display: block;
And I can see that it had display: table; which is now commented out as seen on the screenshot below:
Inspect element screenshot
The problem is that you are putting children divs which have display: table-row; in that display: block; parent and, because they don't have an actual parent with display: table;, their width isn't rendered properly and no CSS for width will apply to them (such as 100%, 75%, 100vw).
Children divs inspect element
On top of that, you have .rwmb-input width set to width: auto;, look at what it does to the image upload field for example:
Screenshot - rwmb-input width auto
I have changed the:
.rwmb-field to { display: flex; }
Screenshot rwmb-field display flex
// which solves the field width
and:
#edittag .rwmb-label ~ .rwmb-input to { width: 75% }
Screenshot rwmb-input width 75
// which restores the (I suppose) normal display functionality
one more fix would be to change the #edittag to:
#edittag {
max-width: none;
}
which would get that beautiful fullscreen edit width (instead of the 800px max-width) but this is WordPress core so it's not up to you guys.
I'll keep using my fix but I hope you guys will update MetaBox and fix this yourselves.