Defining table fields of a class across multiple files breaks auto-complete

How are you using the lua-language-server?

Visual Studio Code Extension (sumneko.lua)

Which OS are you using?

Windows

What is the issue affecting?

Completion

Expected Behaviour

If we have a class such as:

---@class MyClass
MyClass = {
    SomeTable = {
        A = "Something",
    },
}

Then another definition of it in another file (an "extension" of the class):

-- This file extends the MyClass class.

---@class MyClass
local MyClass = MyClass

MyClass.SomeTable.B = "Other thing"

Trying to access MyClass.SomeTable should show both A and B as options in auto-complete.

Actual Behaviour

If the keys of a table within a class are defined across multiple files, auto-complete will not work for them all. If you access these keys however, the hover tooltip will be correct and go-to-definition will work.

This is best understood with an example folder. I've attached it below and its code is also shown in the reproduction steps.

Reproduction steps

If you have a class definition in one file such as:
Class_Main.lua:

---@class MyClass
MyClass = {
    SomeTable = {
        A = "Something",
    },
}

And you try to add keys to SomeTable in another file such as:
Class_Extensions.lua

-- This file extends the MyClass class.

---@class MyClass
local MyClass = MyClass

MyClass.SomeTable.B = "Other thing"

Then trying to access Class.SomeTable. in another file will not show B as an option in auto-complete. B will only show in auto-complete in the file were it was added, despite Class there being tagged with @class - which I would expect to add B to the class definition and not just the local usage of it.

UserCode.lua:

As mentioned previously, if you do access B by typing it manually, the hover tooltip will be correct and Ctrl+Click to go to definition will work as expected.

Additional Notes

Example folder replicating the issue is attached. It's the same example as the one shown above.
LLS_ClassExtensionBug.zip

Log File

No response

Reproduce the issue using Class_Main.lua, Class_Extensions.lua, and UserCode.lua from the report or attached example in the Visual Studio Code extension. Start by tracing completion for MyClass.SomeTable across the files, comparing it with the already-working hover and go-to-definition behavior. Done means completion lists both A and B when the table is accessed from another file.