Sometimes when a source file is opened in Vivado HLS (VHLS) GUI, some lines will have little bugs displayed in front of them. This indicates that the GUI can't find definitions for data types or values in those lines. There are also times when certain functions or variables are not displayed in the Directive Editor GUI. Two general project settings shown in the snapshot below will help resolve these two issues generally. The downside is that GUI may be less responsive, which is often negligible when running the tool on a decent machine.