Overleaf: Bibliography in a different folder

I have a large Overleaf document with a lot of references. It’s useful for us to separate them into a number of .bib files, and to store these in a separate folder, to keep the project easy to navigate. The desired file structure looks like:

.
├── bib
|   ├── bib1.bib
|   └── bib2.bib
└── main.tex

In main.tex, the relevant code is as follows:

usepackage{cite} % Allows for ranges in citations
usepackage{mciteplus}

bibliography{bib/bib1,bib/bib2}

I have also tried other folder names (eg. bibliography), and other formats (eg. bibliography{./bib/bib1,./bib/bib2}, but none work.

I have seen other users get this to work correctly (see How to set a default bib path where all the bib files can refer to it?). Is there some syntax or setting I’m missing?