Pushover action stopped working after updating from OH 2.5.4 to 2.5.11

Hi,
after updated OH 2.5.4 to 2.5.11 my Pushover notifications stopped working. I receive the following error in the logs:

2021-01-09 15:03:47.398 [ERROR] [ntime.internal.engine.RuleEngineImpl] - Rule 'my rule': The name 'sendPushoverMessage' cannot be resolved to an item or type; line 23, column 9, length 64

I’m sending the notification in my rule implementation using:

sendPushoverMessage(pushoverBuilder("Motion detected"))

according to what has been documented here Pushover - Actions | openHAB

I have my actions installed via textual configuration in services/addons.cfg (not via PaperUI):

# A comma-separated list of actions to install (e.g. "action = mail,pushover")
action = pushover

Now, after updating to 2.5.11 I was looking into using the binding instead of the action. So, I changed services/addons.cfg into:

# A comma-separated list of bindings to install (e.g. "binding = sonos,knx,zwave")
binding = astro,avmfritz,bosesoundtouch,exec,http1,hue,icloud,mail,network,ntp,pushover,weather1,systeminfo

# A comma-separated list of actions to install (e.g. "action = mail,pushover")
action = 

Afterwards I restarted the service via:

sudo systemctl restart openhab2

Now, I’m receiving the following error telling me, that the binding couldn’t be installed:

2021-01-10 22:10:44.461 [ERROR] [core.karaf.internal.FeatureInstaller] - Failed installing 'openhab-binding-pushover'

Is there something I have missed?

Tobias

I did a check for any Pushover related feature available via the remote console:

feature:list | grep pushover

and only found

openhab-action-pushover │ 1.14.0   │  │ Uninstalled │ openhab-addons-2.5.11  │ Pushover Action

Is Pushover - Bindings | openHAB only available in OH 3 then?

Update: I’ve tried switching back to the action (basically what I had used before and what was not working after my OH update to 2.5.11).

My services/addons.cfg:

# A comma-separated list of actions to install (e.g. "action = mail,pushover")
action = pushover

Did a restart of openhab:

sudo systemctl restart openhab2.service

and now Pushover started working fine again.

Can anybody help me understanding why it didn’t work initially?