I tested this is both 9.0.4 and 9.0.5 default installs with sample data

Problem:

When editing the choices on a product option from the Options tab, the page is wiping out the sku modifier values if the SKU column is not selected as visible when Save and Close is clicked.

Steps to reproduce:

Launch a default install with sample data
Go into Catalog/Products
Find the Cat or Dog Bowls product. Edit it.
Click the Options tab.
Find the 2nd option 'Bowl Sizes'. Click Manage Choices button on the right for this option.
On initial load, the SKU column is not checked and not visible.
Check the SKU column and click Show Fields To Edit. The SKU column now renders.
Populate the Sku column for every choice. I used '-S', '-M', '-L' and '-XL'
Click Save and Close

You're back on the Options tab. Click Manage Choices again on the Bowl Sizes option.
Uncheck SKU column, then click Show Fields To Edit to apply. The SKU column disappears.
Now click Save and Close.

You just wiped out all of the sku modifiers you previously set.

Click Manage Choices, show the SKU column and you'll see all of the sku modifiers are now gone. Permanently.

Since SKU is not a default selected column during initial page load, this happens on every product you need to update but did not include SKU in the fields to edit. So you have no idea the page is blowing away all of your sku modifiers until hours, days or weeks later.

Edited by user Wednesday, February 23, 2022 3:36:31 PM(UTC)  | Reason: Not specified

Please check with all the fields. We just had a client have variant weights disappear and I just tested by not displaying the weight and saving the choices and it wiped out the weight.

One thing to consider in this routine:

The code is written to persist the selected columns for the user. That's a handy feature. But, it adds the productId to the key when saved to user.Settings(). That means the column settings will only ever persist for that one single product. Pulling up a different product will result in the user reverting to the default two columns again.

It be more useful for the user to have the settings stay regardless of which product they are viewing. Especially in a catalog with thousands of products. It's not like store admins go into that page on a daily basis so the likelihood of an admin benefiting of settings per-product is quite low.