3.9 beta2 still only read-only when using Horde as the backend

[oparoz]

Calendars work fine on various mobile devices, but it impossible to get them to work on TB via this add-on. They always end up as read-only.

• I'm not using autodiscover, but manual setup, which seems to work since I'm being shown a list of root folders
• It's impossible to enable read-write mode
• I'm using Horde to provide the EAS service
• No error in the error console