When using UR series (UR/UR-RT/UR-C) and AXR4 (T/U) on one Windows PC with the TOOLS for UR-C V1.5/Basic FX Suite V1.5, please note the following two points.

Installation order

After installing TOOLS for AXR4, please install TOOLS for UR-C V1.5 or Basic FX Suite V1.5.
If you install in the reverse order, the DAW using the bundled plug-ins may behave unexpectedly. Please uninstall TOOLS for AXR4 and TOOLS for UR-C V1.5 or Basic FX Suite V1.5 and reinstall them in the correct order. 

Uninstallation

Even if you no longer use the UR series after installing the software in the above order, do not uninstall UR-C V1.5 or Basic FX Suite V1.5. If you uninstall it, you will not be able to use the stereo version of the Sweet Spot Morphing Channel Strip plug-in.
If this problem occurs, uninstall TOOLS for AXR4 and then reinstall it.