Getting manufacturerData from custom uuid device

That firmware should be fine. Since you blanked out the data array I can't see if the manufacturer data was actually in the advertising packet or not, but I'd be pretty sure it isn't if it's not being decoded.

Which just leaves whether the data is the the 'scan response' packet - which would require an 'active' scan. That's something that you'd need a 'cutting edge' build for, and then I think NRF.findDevices(print, {active:true}) should do it.