We found an additional problem when switching from ETH to ETC but it seems it depends on the OS and driver version (and affects mostly Linux and only 4 GB AMD cards). We'll be ready with a fix or workaround tomorrow.
OpenCL 19.20 AMD Driver
OS: HiveOS 0.6-144
linux Ядpo 5.0.21-hiveos
4Gb AMD Asus Cards STRIX
Phoenix 5.0d
same problem ETH to ETC mining rejects