Wrong slides order with grid + fill row + loop

[FrancescoMessage]

Check that this is really a bug

• I confirm

Reproduction link

https://codepen.io/ftendi/pen/jOJKBMJ

Bug description

I have a Swiper with 3 columns / 2 rows and grid is filled by rows.
Total number of slides is 12.
My desired fill order is the following:

1..........2..........3         #         7...........8...........9
4..........5..........6         #         10..........11..........12

To obtain this, I've set:

slidesPerView: 3,
slidesPerGroup: 3,
grid: {
    rows: 2,
    fill: 'row'
}

If I also enable loop mode (leaving loopAddBlankSlides as default true), the slides' order is wrong after the first loop.
Slides appearance before the loop is:

1..........2..........3         #         7...........8...........9
4..........5..........6         #         10..........11..........12

Slides appearance after the first loop is:

1..........4..........2         #         7..........10..........8
5..........3..........6         #         11..........9..........12

Expected Behavior

I expect the right order of slides after first loop.

Actual Behavior

The slides' order after first loop is wrong.

Swiper version

11.2.1

Platform/Target and Browser Versions

macOS 15.2 - Chrome 132.0.6834.110

Validations

• Follow our Code of Conduct
• Read the docs.
• Check that there isn't already an issue that request the same feature to avoid creating a duplicate.
• Make sure this is a Swiper issue and not a framework-specific issue

Would you like to open a PR for this bug?

• I'm willing to open a PR

[FrancescoMessage]

Find now an alert in console: "Swiper Loop Warning: Loop mode is not compatible with grid.fill = row".
Ok, but it seems it's not in documentation. Do you think loop mode and grid.fill = row will work in the future? Thanks

[clift26]

I would like to know if this current problem will be fixed in the future).