FabFilter

I notice something weird about the XLFO in Volcano2 and Volcano3 and Saturn1 and Saturn2 for OSX ProTools. Is the following intentional behavior?

1) I create a 16 step XLFO with step #1 all the way up and the remaining 15 steps all the way down (or set to zero). I turn down glide on the XLFO so it has hard rectangular edges. The XLFO's Phase Offset is set to the default 0.000. I associate this XLFO with the volume of the only Volcano3 or Saturn2 band (there's only a single full frequency range band), so the volume spikes every time the XLFO comes back to step #1.

2) The ProTools session has basic tempo (120bpm) and meter (4/4) settings that start at time zero and apply to the entire session, nothing fancy.

3) I play a 4 bar loop of continuous sound, starting at the session's time zero.

4) If I set the XLFO's tempo sync dropdown to 1 bar, the volume spikes quickly when I'd expect at the very beginning of each of the 4 bars that are playing in a loop.

5) If I set the XLFO's tempo sync dropdown to 2 bars, the volume does not spike at the beginnings of bar 1 and bar 3 as I'd expect. It instead spikes at the beginnings of bar 2 and bar 4. Weird.

6) If I set the XLFO's tempo sync dropdown to 4 bars, the volume does not spike at the beginning of bar 1 only, as I'd expect. It instead spikes at the beginning of bar 4. Weird.

7) I've checked and the XLFO is not free running in this scenario. It is actively synced by the plugin to my DAW session bars and tempo. I have not messed with the XLFO midi sync options. I bet I could use them and send midi to the plugin to force it to start at step #1 when I want, but I'd love to avoid that and just have it work intuitively according to DAW tempo and bars without the need to route midi to the plugin.

Its counterintuitive to me that in this scenario where I want the volume to spike at the beginning of every 2 bar section, I can't use step #1 in the 2-bar-long-tempo-synced XLFO, and instead have to use step #9. Is this intentional?

Thanks for the time and help.