Were any flash files recently updated? If so, verify they were the correct ones for the machine.
Most likely you've got a wiring issue on the CAN. I'd also check your power and ground circuits on the machine controller and monitor. I have seen modules throw up CAN communication errors due to ECM power/ground wiring problems.
CID 247 refers specifically to transmission of Data between the various ECMs - "This diagnostic code is caused by network data that is in error between the Machine ECM and the "Monitor Display" ECM through the J1939 Data Link. The data received over the data link is in error."
Based on the fact that no flash files were recently updated it might potentially be a case that an update is required.
Cat Service Mag SEPD1571 - "New Engine software is available for Hydraulic Excavators with TIER 4 Engines - The new engine software includes improvements to the MID 36, CID 247, and FMI 14 Engine ECM: J1939: Special Instruction strategy." That sounds a bit adjacent to the symptoms the OP is posting.
For a 329E the software would be a 417-2968 Part Number. This new software was effective from machine Serial Number PLW01172 and Up, so about 500 machines after the OP's was built.