Linked files need to be open in order to update output file

[Katherine]

We have a very organized structure of excel files where data is input in a series of files and then the output files are opened for the reports - no data entry in the output files. We have an issue where the output file will not fully update, even when "Update" is clicked, until the input files are opened

Does anyone have an idea how or why this occurs, and what can be done to solve this problem? The input files are about 8MB and the output are about 2MB, so we don't want to open every input file in order to update

Thanks