Update: version 0.0.2 fixes the fast-click problem reported by NaviRetlav.
I have developed a workaround to the bug described here that may be suitable for some situations.
It takes the form of a Combinator containing two Thor instances. When the bug is triggered the output from the first Thor is interrupted and this triggers the second Thor to generate a short pulse. This pulse is then used to gate the triggering of the first Thor's Step Sequencer, which has the effect of correctly resetting the Voice and reopening it.
This Combinator can be used to provide a reset pulse to any Thor in your workspace that relies on an open Voice, such as one that is using the Shaper to affect an external sound source (routed into the Thor). This pulse is generated whenever the bug occurs, thereby providing a way to recover from it.
A test-bench for this workaround can be found here (0.0.2). Simply open the file and you'll see the CV Debug combi on the left, and the Reset combi on the right. The top-right Delay device in the CV Debug (labeled "Reset Out") combi shows the state of the pulse. Hit Stop a few times to see the value jump from 1127 to down to 1000 briefly. You can adjust the length of the pulse with the first knob on the combi.
To use this pulse to reset another Thor, simply take this "Reset Out" signal into a CV Input on your Thor and use it as the Scale control (@ 100%) for your "LFO2 -> S.Trig" rule that you are using to retrigger the Step Sequencer. Look at the first Thor in the CV Reset combi for an example of this.
If you find this workaround useful or broken I'd appreciate some feedback please.