Help.I have 365 Premium subscription, it hasn't expired, but I lost access to Copilot on phone.

I'm an Office 365 premium subscriber. I used to be able to use Copilot normally on Office on both my computer and iPhone, but now I can only use Copilot on Office on my computer. When I try to use Copilot on Office on my phone, it says: 'It seems you don't have a valid license. To get access, please contact your admin.' Before this problem happened, I sent an invite link to someone else to use Office 365 with me, and then I clicked the invite link myself on my phone using my subscriber account, and it showed that I successfully joined the sharing. After that, I couldn't use Copilot on Office on my phone anymore. Even though my subscription account is still shown as the organizer in the Family group and my subscription hasn't expired, it seems like I lost access to Copilot on my phone.