When I run RStudio it opens dataframes from previous session (as previously they have been opened with View() command). However they are not in the environment. Is there an easy way to reload them into the environment, as right-clicking and choosing reload does not do it...?
These views are indeed remnants from previous sessions, but if you decided to not save the environment, they will no longer be in memory when R starts, and thus you can't reload them until the variable has been assigned again.
So either save your environment (workspace image) when closing RStudio, or run the code again needed to load the variables.