I'm not sure of the "Custom Tooltip Option" you guys are talking about. Is that in a mod included in the Insomniax Comp?
I did notice however that there is a tooltip mod included with Insomniax already: "Insomniax CustomTooltip v1.2 a modified version of Verona's original by LedMirage"
EDIT: Ok, I didn't put the two together and realize what I was interpreting as a "Custom Tooltip Option" was actually the name of the mod you were referring to.
My first guess is that this mod is conflicting or taking away some of the functionality that TipBuddy provides. First try disabling this mod (if you haven't already) and see if that changes anything. I would also go into the TipBuddy options and set the Anchor Non-Unit Tips dropdown to "Smart" which should always make sure your button tips stay within your screenspace.
Let me know if any of this helps!