DWM1001 -unable to enter sleep mode, but still loose comms

[align=justify]So we’ve been working with DWM1001 on our custom boards, using API commands over UART. The only pins we connect to are: power, ground, UART RX/TX, RDY , RST and BLE wakeup. Everything is awesome on power-up: we draw reasonable current of 50 or so uA and can see the radio do periodic UWB measurement (based on current profile). We then talk to it over UART and follow by issuing API sleep command. The module does not enter sleep and sits at 1.5mA, it also looses communications (we receive timeouts). If we attempt to wake it up by sending a byte over UART it does not recover. It takes full reset to get back to working. [/align]

Tried adding SPI CS pullup to make sure that pin is not floating- no difference. Low power mode is enabled in module settings, and sleep command does not throw any errors. What am I missing here?