I think it is unfortunately a shell gland issue too. Photo of eggs below were taken february 2020. They are the eggs of a then 5-year-old hen. At age 4, she was still laying 5-6 jumbo eggs weekly. (Yes she was an incredible egg-laying machine.) In the photo, those are the first 2 eggs she laid in 2020. Same as your hen, the softshell "holes" were in Exact same place on egg shell. I knew it was an "uh oh" big problem. Until then, her eggs had always been perfectly formed, with hard shells & single yolks only, never double. She had full access to layer feed, oyster shell, & was otherwise in great health.
She never laid another egg last year, although i saw her in the nest boxes many times. So i knew she was laying internally, & didnt expect her to survive through last year. She did. And made it through this past winter. Until she again resumed "egg-laying" in february 2021. I saw her in the nest boxes at least twice, but never any of her eggs. She sadly passed away just 2 days ago. She was a special girl. I miss her a lot & always will.
Your hen is much younger than mine was when the problem began. If your hen's issue rectifies itself, please let us know. Hoping for the best for you both.
She never laid another egg last year, although i saw her in the nest boxes many times. So i knew she was laying internally, & didnt expect her to survive through last year. She did. And made it through this past winter. Until she again resumed "egg-laying" in february 2021. I saw her in the nest boxes at least twice, but never any of her eggs. She sadly passed away just 2 days ago. She was a special girl. I miss her a lot & always will.
Your hen is much younger than mine was when the problem began. If your hen's issue rectifies itself, please let us know. Hoping for the best for you both.