Hi @taddandrle,
There was recently an issue that Amazon had where they reported that user’s drives had no files. This caused all files to be turned back into placeholders, once they corrected the issue. See here for more details: Sudden Disappearance of all Amazon Drive Files - 2017 - 01 - 23 - * RESOLVED *
Aside from that issue, files should stay locally cached unless they are unsynced. Do you have an auto-unsync rules in place? https://docs.odrive.com/docs/manage-disk-space#section-configure-auto-unsync