To Grid By Shape in 2.91

[Jamie-txt]

I saw the previous post by boski05 but I haven't been able to find a work around for a similar problem in v2.91.2 with a newly installed copy of UV Squares.

Is there a solution for this or am I doing something wrong?

Here is the behaviour for reference.

Select linked 'L'

Align 'To Grid By Shape'

[Radivarig]

Interesting, can you attach the .blend file?

[Jamie-txt]

https://drive.google.com/file/d/1w7GpQVU7KWBLlxfWjPEktKm8l5mYRzuN/view?usp=sharing

[Radivarig]

You have subdivided the seam edges making their faces have more than 4 vertices and non-quads are not supported.

You can select all vertices that are not at the face corners and press G twice to slide them along completely to the face corners, then use F3 > Merge by Distance to remove doubles, then use the addon again.