Amanda went on to claim that Bob is suffering deeply regarding the rocky relationship but is dealing with it privately, adding that the 82-year-old's health inhibits him from speaking on the matter.
This devastating feud was brought back into public consciousness after Bindi responded to a comment questioning why she had excluded her grandfather from a Father's Day tribute.
In the since-deleted response, Bindi wrote: "I really wish that my entire family could spend time with Grace. Unfortunately, my grandfather Bob has shown no interest in spending time with me or my family."
The 22-year-old went on to claim that Bob has returned her gifts after opening them and even called his behaviour "psychological abuse".
"He has ignored me, preferring to spend time doing anything else rather than being with me," she wrote. "He has never said a single kind word to me personally. It breaks my heart."
Bob's relationship with his daughter-in-law and grandkids has been turbulent since the tragic death of his son Steve.
Just 18 months after Steve lost his life in 2006, his widow Terri had a reported falling out with Bob, prompting the Crocodile Hunter's father to leave Australia Zoo in March 2008.
The feud was said to be about a disagreement surrounding the direction of the zoo. Bob, who established what would eventually become Australia Zoo, was apparently concerned the wildlife park was becoming over-commercialised.
"Steve's ultimate passion, even from a young boy, was always for the conservation of Australian wildlife and its habitat," Bob wrote in a statement at the time. "When Judy (Bob's late second wife) and I move to our new property we intend to carry on with wildlife rehabilitation and conservation projects and therefore continue Steve's and my dream."
Australia Zoo also released a statement, denying rumours of a rift between the two families.
"Bob is a gentleman of retirement age and we fully support and love him dearly. He has been through so much grief with the loss of his first wife Lyn and only son. These rumours need to end in respect to the Irwin family."
WATCH: Terri Irwin reveals the promise she made to Steve Irwin before he died (Story continues after video)
Despite the denial, in an episode of Australian Story, Bob's friend Amanda confirmed that there was "break" in the family.
The conservationist himself got extremely candid about what happened at the zoo after Steve's death and what prompted his departure.
"I just felt that it was better for everybody concerned if I left Australia Zoo and Judy and I and all our friends were able to continue Steve's work the way I believe it should be done, Bob said on the program.
"The problem I had was that the management and I didn't agree on certain aspects of Australia Zoo after Steve's passing… because most times I went into Australia Zoo, I would have a different sort of opinion with somebody… or I may have an idea and it would not be listened to."
When Bindi and Chandler tied the knot in 2020, Bob did not receive an invitation to the ceremony.
After news of their engagement hit the media sphere, the conservationist shared his support for the young couple, telling the Courier Mail, "Much the same as any other parent or grandparent, I would wish them all the best — which I do — and hope things go really, really well".
Towards the end of 2020, when Bindi and Chandler were preparing to welcome Grace Warrior into the world, a source told New Idea that Bob was missing his family greatly.
“He misses Bindi and Robert and now he’s having to contend with the fact that she’s a grown, married woman with a baby on the way – a great-granddaughter,” the source revealed.
“He knows in his bones he will never be allowed to meet [the baby]. Only over Terri’s dead body would that happen."
Despite the decades-long silence between Bob and the Irwins, the sourced claimed that Bob was hopeful he may one day be welcomed back into the fold.
“Still, he can’t help but harbour a little hope Bindi will one day decide – hopefully before it’s too late – to end the blanket ban on his presence in their lives.
“He feels Bindi’s child should meet her paternal great- grandfather. After all, he is the man who started the Australia Zoo and the Crocodile Hunter legacy, that Bindi and Chandler’s little girl will one day inherit.
“He hopes Bindi will take pity on a very old man,” added the source.
Bob announced his retirement three years ago, claiming it was time to "pass the baton".
"While wildlife and conservation will always remain Bob's driving force, he will no longer be making public appearances on behalf of the Bob Irwin Wildlife & Conservation Foundation," read a statement.
"Bob is optimistic about the future of our planet because of your dedication to conserving our incredible wildlife and its habitats."