I have the exact same problem. Since the synapse program may be the slowest small program in PC history, it takes some time for it to actually find out that the mamba exist in wireless mode. In the meantime the sense-changing buttons works perfectly as intended. The same as in wired mode. After a few minutes, exactly when the slowest program on earth (Synapse) detects the mamba, everything goes to shit. Sense doesnt work, led lights bugs out, and if you change in desperate ways, up-and-down in frustration, it will change several times over the next hour or so. Nothing works as intended in wireless mode, so I have a wireless mouse that doesnt work wireless with the only supportet drivers; Synapse.
This has been going on for months now, and i believe I've tried everything, but with Synapse installed, nothing works besides in wired mode. Nothing to complain over there, but if i'd knew it wouldnt work in wireless mode, I'd rather buy a wired mouse. Updates are rolling in, but fixing this problem doesnt seem very likely. Months are passing, but no fix. Never more Razer (only because Synapse).