EDI Exporting through BPM

We are having an issue getting our EDI text files to export consistently. We can think of any rhyme or reason why it is hit or miss. We have a BPM that exports the Epicor EDI text file when the record in the TTInvcHed table matching those requirements. Is there anything that would cause the server to miss those records as they processed? Some days we get all the EDI files, some days some, some day none. I don’t have a real good understanding on BPMs. Can server performance affect the way BPMs are ran?