Subject of the issue

Nested grids with disableOneColumnMode set to false seem to :

1. fall well to one column when width goes low, but fail recovering their columns when width "slowly" re-increases
2. keep their columns when webpage loads directly with low width

Your environment

• version of gridstack.js : gridstack-h5.js v3.1.2
• browser : Chrome 87.0.4280.88 / Firefox 68.12esr

Steps to reproduce => Actual behavior

https://jsfiddle.net/zh2rabyg/

1. reduce width to get one column view, then slowly increase width => main grid recovers its columns, but nested ones do not
2. reduce width to get one column view, the re-run the fiddle => main grid is one column-ed ; but nested ones are not

Expected behavior

Nested grids should behave the same as main grid.