Do not load() .m files. If they contain commands, then execute them, possibly with run() . If they contain data, then use a different file extension and an appropriate import routine.
load() of text files should only be used for rectangular numeric blocks that use space for the delimiter and either have no header at all or else use lines starting with % as the header.
You cannot use load() to read csv-type files
Note: if used save() to create the file and you did not use the -ASCII option at the time you saved, then the file would have been created as binary in mat file format even if you used .m as the file extension, but MATLAB would then expect text format when you tried to load the resulting file because of the .m extension. If you accidentally saved in mat file binary format to a .m file, then rename it to have .mat extension.