Frost bomb and stormweaver +2 limit not stacking with +1 from "Secrets of the Orb"

My goal is to generate as much ice infusions as possible so I wanted to make use of Stormweaver's +2 limit and spell cascade on an frost bomb to summon 3 bombs simultaneously to bypass the cooldown. This works perfectly and drops 3 ice infusions on completion. I then notice that there is a passive on the skill tree called "Secrets of the Orb" that states that "Orb skills have +1 to Limit". This in combination of the +2 limit should give me 4 simultaneous frost bombs right? So this time I link frost bomb to spell cascade and spell echo which (I think) should give me the last bomb I need to hit my limit of 4. The end result of this is 3 ice infusions.

I did some further testing. I unspeced out of Secrets of the Orb and only used the +2 limit from the ascendancy. I then used frost bomb linked to spell echo yielded me two ice infusions at the end. I unspeced out the limit ascendancy and tried only using Secrets of the Orb and the result of the above test was one ice infusion. In this test, the spell echo did not create another bomb but simply refreshed the initial bomb. Why does the bomb refresh and not create with +1 limit but in another scenario with +2 limit it works as it should?

In conclusion, I think Secrets of the Orb is not working as it should with frost bomb when it works clearly fine with the Stormweaver ascendancy. To be fair, the wording of Secrets of the Orb is slightly different to the wording of the ascendancy node but it that shouldn't affect the spell echo test I did at the very least. Perhaps my test were not sufficient and feel free to correct me on any of my assumptions or tests. Thanks as always for the great game!