So basically, when adding pattern in loom without any single navigating in UI, it works, but when creating pattern after navigating the UI, the arrows and box grid disappears.

What arrows are you talking about? I don't see anything wrong in either the video or the screenshot, just the selected banner, which appears two instead of 1

@Wilyicaro basically these. Sometimes it can disappear inside the crafting types when using it, and also on loom as well.

turns out, the arrows can disappear sometimes on the crafting tabs

Fixed in version 1.6.4, thanks for reporting.