Solution
Only PXIe Chassis that support 82 W of slot cooling capacity (such as the PXIe-1092 or PXIe-1095) support the PXIe-8881.
When used in a PXIe Chassis with less cooling capacity, the PXIe-8881 will just put itself into a low-power state if and only if a compatible version of PXI Platform Services is installed and the NI PXI Resource Manager Service is set to Active (running). The message shown in NI-MAX confirms that the controller went into a low-power state, in which, basically, its CPU power is limited.
Operation and performance are not guaranteed in other PXIe Chassis, so NI warns customers that they are using the PXIe-8881 in an unsupported PXIe Chassis.