When using new release of P66 inverter, some user might face communication issue, which could be as displaying ILF (communication board interruption) in the inverter display or losing not been able to detect the inverter in the I/O mapping / SDM. while if this inverter has been swapped with another P66 but old release it could work just fine without issue.
This is basically behavior is happening because there is some update happened on the software of the drive with the newest release.
Therefore, the solution for this issue would simply be one of two options:
1- Install the later HW upgrade for the inverter from B&R website
2- Upgrade the used project to the latest Automation Runtime available.
Those two steps will solve this issue completely.