In the event that the controller loses connection to Optics (e.g.: during a server-side software update, Internet outage, etc.), the controller is designed to save a certain amount of data locally and then upload that to OpticsRE when the connection is reestablished.
Prerequisite: for this to take place, the controller must have a formatted SD card installed with enough room left on it for data to be saved. If this prerequisite is not met, the data during the outage will not be available in OpticsRE.
Caveat: while the controllers are designed to act in this way, we have seen cases where uploading the saved data (the "Replay" file, *.rpy) fails. Should that occur, the data will also not be available in OpticsRE.
Making sure your controller is running the latest firmware version (see here: http://www.outbackpower.com/resources-mobile/technical-support/firmware-updates) will help reduce the number of such failures. As other reasons for possible failures are found and detected, the fix is built into the then-current patch release. Several fixes are being built into the next firmware releases which will come out after the date of this publication (Feb. 20th, 2018). The upcoming Mate3 firmware release, 3.15.7 is expected to fix several causes of this issue.