Beds24 have done sterling work over the last year extending their functionality to ensure that their software works with the Jomres CMF REST API functionality.
When you first start using Jomres, if you need to connect to a channel manager, Beds24 REST API is a great choice providing that all of your properties are SRPs (Single room properties, in Jomres-speak, e.g. Villas, apartments etc).
If, however, your properties are hotels, bed and breakfasts etc then instead of using their REST API functionality, you're better off using the Jomres Beds24v2 plugin.
This is to due with how the two connecting systems work.
The Beds24v2 plugin manages sending and fetching updates from the Beds24 servers. In the event that another OTA updates Beds24 with a change then Beds24 will call your Jomres installation and say "There's an update" and the Beds24v2 plugin will then fetch the update information. This plugin is best used if you have MRPs (hotels, etc, where you rent out rooms in the property) and you want to use the Jomres UI as your primary configuration UI.
The Beds24 REST API functionality works very differently. In this configuration Jomres is treated as any other OTA. Beds24 have direct access to the Jomres database through the API keys you save against your account on their server via the CMF REST API feature plugin. The limitation is that your properties need to be SRPs (Villas, apartments etc, where you rent out the entire property).
If you are using the Beds24v2 plugin's functionality, you should not have the Channel Management Framework or the API Feature CMF installed. If you do, please uninstall them as conflicting information may be sent to and from the two systems.