That is because the sizes are Blocks, with the text on a different layer than the lasso. It is unfortunate that the LAYISO command does not respect blocks like LAYFREEZE does.
But depending on what you are doing, there are easy workarounds. If your intention was to delete them all, you can use LAYDEL or our Delete Station.
Alternately, you use LAYFREEZE to somewhat quickly freeze the layers you don't want, and then save that layer state.
Lastly, you could use XLIST to check the layer the text is on, and isolate that layer along with the pipe label layer.

--J