missing symbols for full deobfuscation?

Hi,

I'm currently working on a project in which the call stacks I get back from Android don't say the name of the library for the symbols I should use; instead it just says something like this:

/data/app/com.company.appname-zJx7CSf3WHyOBDE2V0-LsA==/base.apk (BuildId: 3fc12a11c0cc6449f6857a430ff49abffaea833f)

Where "base.apk" is the library; which is not very helpful to me :/

I've done a lot of searching, but haven't seen any information about this specifically, and am baffled as to why it turns out this way; it ends up being a guessing game as to which symbols might deobfuscate which addresses.
The only symbol that is output by the build is the libil2cpp.sym.so; that plus the Unity Editor libunity.sym.so, are the only symbols I have.

When run the addr2line tool using both symbols, I still end up with gaps in my call stack
(could these be 3rd party function calls that need those symbols?)
by "gaps", I mean lines that don't get obfuscated and are left empty with a question mark, like this:

??
??:0

Is there any way to get the Android crash logs to tell me what the actual library symbol files I need are, instead of saying my project name '.apk'?
Does anyone know why this happens and if there's a way to change it?

I've tried making some other blank projects, and they work fine, but this is a bigger project with many settings that I could be completely unaware of - unfortunately, due to the nature of the project, I'm not at liberty to discuss what it is or much about it outside of checking basic configs.

 

A quick update, I think I found out the the "base.apk" is showing up there because the project is building a split apk build.

if anyone knows more about symbols with regards to split apk's, please post something here. I've been scouring the internet to no avail