Subject of the issue

Resizing from a small screen to a larger screen doesn't set correct widget dimension when rescaled

Your environment

Whatever is live on https://gridstackjs.com/ ( I think it's 2.1.0 )
Google Chrome Version 86.0.4240.198 (Official Build) (64-bit)

Steps to reproduce

Gridstack demo itself can be used to replicate the behaviour
https://gridstackjs.com/

1. Resize your window to something smaller than 848px
2. Open https://gridstackjs.com/. Scroll down to the grid. The grid should be in one column mode.
3. Start increasing the size of the window by dragging it, after it becomes larger than 848px, the grid should go into "grid" mode from "onecolumn" mode
   12 columns appear but all the widgets stay on the first column.

Expected behaviour

The widgets dimension and position should be reset correctly.

Actual behaviour

Widgets stay on the first column itself and doesn't put itself in the correct position.

Here's a GIF of the behaviour

Expected result after resizing