The PREV_TARGET variable was defined as a Shiny-wide global constant such that it could be shared between user sessions. However, each user session modifies PREV_TARGET out of its own environment with <<- which means the constant is changing for other users! Move PREV_TARGET to be defined in the beginning of the server function to keep it tied to a particular user session.
The
PREV_TARGETvariable was defined as a Shiny-wide global constant such that it could be shared between user sessions. However, each user session modifiesPREV_TARGETout of its own environment with<<-which means the constant is changing for other users! MovePREV_TARGETto be defined in the beginning of theserverfunction to keep it tied to a particular user session.