Report formulas stop working when opening a second report

I am having issues with opening multiple Intelligence Reporting reports from the same company database.  If I only have one open everything is fine and works well but if I open a second one (from the same company database) all of the formulas from the first report stop working.  If I try to add a new formula it also doesn't work.  It's incredibly frustrating to have to close and re-run the first report.  Is there a way to refresh the first report or a way to stop this from happening?  I know it has to be a Microsoft issue as I've been using IR for years and it's only become an issue recently but have no idea how to fix it.