In your settings, the bash command associated with BibTeX is:
bibtex build/%. It means: "look for the (implicitely said
.aux) file in following folder:
<location of the .tex file you're compiling>/build".
This is handy when you tell (pdf)LaTeX to put every temporary/auxiliary files in a subfolder (here name
build) in order to keep the original folder "clean". You activate this behavior using the
-output-directory option while running (pdf)LaTeX (e.g.,
pdflatex -output-directory=build/ %.tex).
However, since you did not enabled this feature (i.e., the bash command used for (pdf)LaTeX compiling does not call the
-output-directory option), all temp files are created in the same folder than the
.tex file you are compiling.
But in your case,
bibtex is still looking for the
.aux-file in a non-existing subfolder named
Thus, you should tell
bibtex to look for the
.aux file in the same folder than your
.tex file, i.e. write
bibtex % instead of
bibtex build/% at the BibTeX line.
(Or you could also create a subfolder named
build, and use following commands: pdfLaTeX:
pdflatex -output-directory=build/ %.tex; bibTeX:
bibtex build/%. But you would also need to update paths for other commands (e.g. pdf-viewer).)