When charging various teleporter devices (receiver, transmitter, dialer etc), the power storage number loops around after 32768 and goes into negative. This only happens on the UI though, and the blocks still appear to be holding the correct amount of RF. The bug occurs only in SMP: it's fine in SP.
Tested with the latest version, 1.30.

I can reproduce this. Very weird. I will investigate. Thanks for reporting

Fixed in next version (1.31)