Calibrated Ha Doesn't Look Correct - Too White in Middle

Hello,

New user here

and was hoping I could get a bit of help with a problem.  I've taken mono L, Ha, R,G,B images with the 1600mm Pro and have used APP to calibrate each channel.  The calibrated LRGB lights look good, but the calibrated Ha lights seem to bright in the middle - They don't look correct.  My details are as follows:

L - Using 50 Gain, 10 offset and Exposure of 45sec. Darks at 240 sec. @ 50 Gain. Flats & DarkFlats of 50 Gain @ same exposure times using NINA's FlatsWizard.

RGB - Using 50 Gain, 10 offset, and exposure of 60 sec. Darks at 60 sec. @ 50 Gain. Flats & DarkFlats of 50 Gain @ same exposure times using NINA's FlatsWizard.

Ha - Using 139 Gain, 10 offset, and exposure of 240 sec. Darks at 240 sec. @ 139 Gain. Flats & DarkFlats of 139 Gain @ same exposure times using NINA's FlatsWizard.

I was thinking it was related to the flats or dark flats, but when I calibrate the Ha frames using only lights and darks I still get the same issue of a brighter area in the center of the calibrated lights.

Attached are images of the lights (linear) and Lights (Calibrated).  You can see the brightening of the image center in the calibrated frame. Also included images of my D, DF, F, MDF, and MF for reference.  

Not sure what I'm doing wrong, I'm very new to this.  Going a bit crazy here : )

Thanks,

Joe