Current flow with a potential difference
In CMOS circuits there is dynamic current flow and it is from one of the power rails to the parasitic capacitance on the output, there is no "closed path" but the current still flows.


There is a closed path. The parasitic capacitance allows current to flow (momentarily) when the voltage on one side of it is changing, thus closing the path.

But this doesn't mean it flows with only one connection to the reference node. The power supply needs to connect from the reference node to the Vdd supply of the CMOS circuit, so that a complete circuit is formed, for current to flow.


  There will be EHP recombination at this reference point.


Electron-hole recombination only happens in semiconductors. It happens (as a net effect) whenever the product of elecron and hole population densities is greater than the square of the intrinsic population density (i.e. \$np&gt;n_i^2\$). It has nothing to do with whether the semiconductor is at the reference point or not.