What is your roku model number and current Roku OS? Try to manually update the Roku OS (Settings...System...System Update...Check Now.)
Interestingly, the issue you started having was reported by users back in Jan 2021, so not unique to you. (asking for subscription) There were a couple of workarounds to try (similar to your original posting, but in a specific order and did not work for everyone. Does appear that HBO has finally recognized it is a problem with their app developed for the Roku and will be developing a completely new app for the Roku and others (they have not stopped trying to fix the current one.)
Here is an article to read on the workarounds and the info regarding the app development I mentioned above. https://piunikaweb.com/2021/08/13/hbo-max-app-crashes-on-roku-devices/ At bottom of article, updated August 13, 2021 mentions the new app development. This article uses a Vulture tech article as reference detailing the problem located at https://www.vulture.com/article/hbo-max-app-crash-problem-fix.html
Maybe others who have found some temporary workarounds can offer some additional help and I will try to see if I can find some as well for you to try. Does seem to be a HBO problem and affects the Roku platform primarily which is why you have no problems using it on your other devices. Unfortunately, seems unfixable for many depending on which Roku device they are currently using. Each time HBO released a fix, seemed to break it on another Roku device. Wish I could give you better news currently.
Roku Community Streaming Expert
Just another Roku user... I am not a Roku employee.
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