The following technical issues have been resolved in ColorProof 22.214.171.124. Please note that the list describes the original problem, not the solution.
Epson SC-S80600 White did not print behind Control Strip
Printing a control strip on a job containing a white channel using CMYK+White print mode, did not print white ink behind the control strip unless the option 'Add Coating Channel: Full Frame' or 'Add Coating Channel : Only Non-Transparent Areas' was selected. [US-22268]
WebClient - Error during installation
During the update of ColorProof 126.96.36.199 to 188.8.131.52 a WebClient error showed up: 'A newer version of this application is already installed on this computer. If you wish to install this version, please uninstall the newer version first'. [04828, 04852, 04956]
Paper tint of CMYK MXD profile was not printed for images with spot colors only
No paper tint was printed in OpenColor jobs with images containing spot colors only (db3), in combination with an MXD profile containing only CMYK. 
Workflow with copies and nesting
If ' 4x copies per job' was defined in a workflow with nesting, the workflow generated 4 jobs with 4 images (instead of 1 job with 4 images). The history however only listed 1 job. [04864, 4637, 04927]
Special characters in channel name - 'Wrong or missing parameters'
CMYK channels in OpenColor jobs were not mapped automatically to the OpenColor project, if the PDF contained one or more channels with & (ampersand) in the channel name. Error messages: 'OpenColor service: Wrong or missing parameters', as well as: 'Selected OpenColor Project has changed', even after synchronization. [UK-9869]
Channel mapping rule with decimal values on German localization
Channel mapping rule sets could not be saved on the German ColorProof localization if the set contained a rule which defined LAB values with decimal values. Error message: 'XML parser error'. 
Channel mapping rule set with *
Channel mapping did not work in OpenColor Jobs if the input channel name in the rule set contained an asterisk (e.g. White*) and the action was 'Define Spot Color'.