GND fill zone creates isolated islands

I am using FreeRouting to route my board. I have created a fill zone on the Back Layer (B.Cu)
and filled it. After the routing stage I get some ground pins that are in “isolated” island and are in fact not
grounded. No error messages or indications that something failed. The boards were ordered and when I tested the boards I found the grounds to most of the IC’s not connected. I’ve included a snap shot of the PCB image, note pin 20 which should be GND is in fact isolated.

I’m rather new to KiCad (or any CAD honestly), going up a steep learning curve, but any help will
be greatly appreciated.
I can upload the entire project if needed.
cheers

Here’s how to promote your level to be able to attach files.

If you run the Design Rules Checker it should report unconnected items.
Also I always turn off both copper layers, silkscreen, f-fab as a minimum and look for any rats nest lines that are still visible. This should ensure you have no stray unconnected tracks. You can add vias to connect top and bottom flood filled zones.

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The 2 rats nest lines pointing to the island should give some clue that the routing is incomplete even without running DRC

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If this is about FreeRouter then it is not KiCad question.
If it is about DRC not complaining than it have to be KiCad bug.
But I rather suppose you just missed the last sentence of PCB Design Workflow at the beginning of:

saying:
“When the board layout is complete and the board has passed the Design Rules Check (DRC), fabrication outputs are generated …”.