I setup a Ender IO capacitor that held a charge of 2.15 billion and the flux plug stopped working and the max send got set to -2144968296 RF/T. Seems to work fine if the charge in the capacitor is below that as it is working with 2.125 billion

Another point: The flux plugs don't work with Cryo-Stabilized Fluxduct. It connects however it does not send any RF

hey man,
this has been fixed in newer versions, see:
#153

probably not gonna be fixed since this is 1.10 and the mod is maintained to 1.12

As far as i can tell from reading other bug reports on the same issue ( i have the sme issue) is that if the power storage (mainly enderio capacitors and draconic spheres) that are capable of storing more than 2.14 Billion RF it causes this issue.

Yes, sorry 1.10.2 is not longer supported.