There is a firmware update available to the Nimbus+ that should fix the issues you are describing. Can you follow the steps below to update your firmware?
Install or update SteelSeries Engine on a PC or Mac device. The firmware update is only available on Engine version 3.18.3 or later. After installing or updating Engine, please restart your computer.
Make sure the device is off. If your controller is frozen and stuck on, you must wait for the battery to drain before you can start the update.
Use a Lightning cable to plug the device into a computer. The device should show up in SteelSeries Engine.
Click the red "Critical Update" bar to install the firmware update. Do not unplug the device during this update, or you could brick the device.
When the update is complete, the controller will reconnect to your computer and show a successful update. The controller should be on firmware version 1.0.1.0, which you can confirm by clicking the gear icon next to the device in Engine.