There's a resonator on this portal, which cannot be bombed: ll=60.402012,25.106766&z=18&pll=60.402012,25.106766
The portal remains green with this single resonator, which should have been removed from the portal after bombing it.
Thanks for reaching out, @ElMusti! Once the XM of the resonator is nullified the portal in question will become neutral. If it's still there, please reach out via in-app support along with a short video. We'll take a closer look at it.
I have encoutered this problem from time to time. Putting a beacon on the portal is a fix weirdly enough.
This also happened to me back on July 9th while doing a banner for Second Sunday. As you can see, we turned the rest of the park blue, but no matter how many bursters I fired at this portal, it would not die. It wasn't being recharged. Intel showed 5% health the entire time. The portal wouldn't receive damage, it was like I was firing at nothing.
Thanks for the tip, @AgentnavnetDitt. I'll keep that in mind if I see this again.