scv.pl.velocity subset on groups not working

[SyrupBadger]

Hi,
I am pretty new to using the scvelo package but so far everything seems to work great with it. However, I am having an issue when plotting phase and velocity for individual genes. My sample has 11 clusters and I would like to only show the results for a certain subset of those clusters. Following through the API for this function I entered the following:
scv.pl.velocity(adata, ['Prg4'], groups=['3', '4','5'], color='tree.ident')
Where the groups represent the clusters that I am interested in. However, the output from this is exactly the same as when I do the analysis for all cells. Regardless of what I enter into the group variable I always get the same set of graphs. I am missing something here ?
Thanks