libicuio.so not found at runtime

I'm writing a program that needs to build .mat files. I compile just fine, but when I run I get:

> error while loading shared libraries: libicuio.so.59: cannot open shared file: No such file or directory

• LD_LIBRARY_PATH is set to /opt/MATLAB/R2018b/bin/glnxa64
• libicuio.so.59 exists at that location
• I have also created a libmat.conf file in etc/ld.so.conf.d/ while looking for solutions -- didn't work.

Has anyone had this problem before?

(As a side note: I also get compiler warnings that "libicuuc.so.55, needed by libxml2.so, may conflict with libicuuc.so.59" and "libicudata.so.55, needed by libicuuc.so.55, may conflict with libicudata.so.59". No warnings about libicuio.so.59, however.)