How to set a comment on a struct member after creation?

[camprevail]

Trying to figure out how to add a comment to a struct member after the member has already been created. I tried using std::core::set_pattern_comment but it just made imhex crash. I could not a single example of this function on all of github so I don't know if I'm using it right... I'm also not sure what exactly what is allowed in the first arg pattern type.
Here's what I tried. I want to attach a comment to the flags member after it's been combined with more_flags.

struct AP2PlaceObjectTag {
    u32 flags1 [[format_read("fmt_read_int_to_hex")]];
    u64 flags = null;
    if (flags1 & 0x80000000) {
        u32 more_flags;
        flags = flags1 | (more_flags << 32);
    } else {
        flags = flags1;
    }
    str combined_flags = fmt_read_int_to_hex(flags);
    std::core::set_pattern_comment(flags1, std::format("Total flags: {}", combined_flags)); //crashes here
    ```