I’ve been in the same situation since April, using iPhone 8 Plus. My shop stopped working completely, so eventually I started using my gf’s phone in order to spend coins. Then, her phone got the same shop bug. This means I’ve missed out on community day bundles, remote raid bundles, a lot of the 1 coin bundles, and now even daily free boxes.
My 8+ had been starting to get pretty beat up, and slowing down a bit performance-wise, so I pulled the trigger on a brand new 11 Pro Max. It came in yesterday. To my delight, I pulled up PoGo and was able to use up hundreds of coins from gyms, that had been just piling up. Sweet relief!! To celebrate, I decided to buy $20 of coins and load up for some remote raid action. I see the coins added to the top right, but the green pokeball keeps spinning....it can’t be, right? Don’t do this to me!! Yep, got my 2500 coins, but now my shop is busted AGAIN, on a brand NEW phone, right after it was working fine and I was thrilled lol. So disappointing.
TLDR— same issue since April, got new iPhone for unrelated reasons, shop let me spend coins but broke again completely when purchasing more.