Drobo 5c random disconnects while mac sleeps

Using Drobo 5C on a Macbook Pro 16 2019 model, Big Sur all latest updates, I get NUMEROUS random disconnects (disc ejected improperly messages from Big Sur notifications) during mac sleep.
It wakes mac from sleep, registers drive ejected improperly, then mac sleeps again, can be up to a dozen times per night. This is unacceptable. I use Apple original thunderbolt 3 cable directly hooked up to my macbook pro thunderbolt port. Tested with other cables. Did a full clean (with drive format) reinstall of Big Sur. Drobo firmware and Drobo dashboard all updated. Please advise.