The following technical issues have been resolved in ColorProof 22.214.171.1246. Please note that the list describes the original problem, not the solution.
DotProof - Epson Stylus WT7900 - 1-bit TIFF
1-bit TIFF files could not be printed in DotProof Jobs for Epson Stylus Pro WT7900. The jobs aborted with the following error: "Error initializing printer queue". 
DotProof - Epson Stylus Pro 7880 - LEN files could not be printed
LEN files could not be printed in DotProof Jobs for Epson Stylus Pro 7880. 
Local installation - 'OpenColor output license for network connection' needed
Even though ColorProof and OpenColor were installed on the same system, the ColorProof jobs aborted with the error: 'Your license only permits a local OpenColor connection. Either install and use OpenColor on the same computer as ColorProof, or obtain a license for using OpenColor as a server on a different system.' The workaround was to provide this license. 
SmartHotfolder and MXN-Profile - Blank Output
ColorProof-Jobs containing an OpenColor-ProofStandard and generated by a SmartHotfolder were processed, however only paper tint was present on the proof, nothing was printed.