I am also having this issue with the "Merge to HDR Pro" function in both LR5.2 and PSCC. When the image is viewed at 50% image size in the HDR app everything appears fine. However, once you start to zoom in the image begins to crop out segements starting on the right hand side. See the screen shots below:
Image at 50%
Image at 66%
Image at 100%
MacBook Pro 2.7 GHz Intel Core i7 16GB RAM 512GB SSD (early 2013) NVidia GT650M Mac OS X 10.9