When using file name format fooN.vtk, "Open" shows VTK file series as group, but loads it as multiple groups instead.
As in the title, if you have a VTK file series named fooN.vtk, it'll appear as a single file group in "Open" but loading divided file series. This problem is solved though when you use the file format foo_N.vtk.
Link for images: https://discourse.paraview.org/t/vtk-files-appear-as-series-in-file-loader-but-are-separated-when-loeaded-in/12196/3?u=bloop
Edited by Rafael Bagood