Hi Jeff,
were you able to fix this with the NDI Tools version you still want to use?
Looks to me there is a fix in 6.0.1.0 (out of NDI 6.0.1.0 Changes: Resolved an issue where the NDI Tools registration state was not being saved correctly), which obviously does address issues on this topic within 6.0.0.0, while I do not remember if I ever had this with the 5.6.1.0 you still seem to use.