Dr. Lin and I discussed this on a recent Forum Friday podcast on social media.
While pictures are very helpful, formula ratios would allow us to provide more useful input. At first glance I would say you may need some mono diglycerides to emulsify better and get the crumb more even. One option that could be available to you is the J&K Ingredients 10-Potato bread mix. J&K Ingredients ship to many distributors all over the world, and there may be one near to you, or if you can receive full container loads you might contact them directly. This is an excellent potato roll base that is used at 10% of the flour weight. The base/mix has all of the micro ingredients, like emulsifiers and dough conditioners precisely dosed for you in an easy way to manage consistent production.
Please do let us know if this helps answer your question.