How to make attribute proc macros more user-friendly with RA

I am working on an attribute-like proc macro, which is intended to annotate functions, as such:

#[my_attribute]
pub fn(arg1: T1, arg2: T2) {
    // User code here
}

The thing is, even though my attribute is only meant to do some semantic checks and is not even modifying the function body, once I annotate the function with my attribute, rust analyzer gives up and stops doing most of its usual tasks:

• Auto-completion works, but semi-consistently. Sometimes completions do not load until after I've written a large part of the call, whereas typically I can get a list of completion candidates simply by typing a . after an identifier.
• Syntax errors are not highlighted at the place where they occur, and I instead get large parts of the function marked as a syntax error.

Attribute-like proc macros seem to be supported in RA to some extent. For instance, I use often use the profiling (https://crates.io/crates/profiling) crate and I don't seem to encounter those issues when using their #[profiling::function] attribute macro. I had a look at the implementation here and I can't see any difference with my implementation.

How does the mechanism in RA that expands proc macros work? Is there a way I can improve the user experience of my macro so that RA behaves just like when writing a regular function?

Start by tracing rust-analyzer's proc-macro expansion behavior and compare it with the profiling crate's attribute macro implementation at profiling-procmacros/src/lib.rs. Reproduce the completion and syntax-error problems with the described annotated function; done means identifying a concrete difference or reproducible rust-analyzer defect and documenting the expected behavior.