We had an issue recently where the branding/logo completely disappeared on our emails. In troubleshooting, we found that one solution suggested online was to just remove the logo and re-add it. We've removed it, and now the 'upload logo' button is dead. We click it and nothing happens. This started about the time I let my subscription go, even though all indicators online are that the plugin will keep working... I may let the subscription lapse again in the future and don't want this to happen again (loss of branding, plugin issues).
My subscription has been renewed for 2 months (thank you to the support person initially helping me based on a Facebook message). But, the button is still not working.