Drag'n'drop event moving gone in Calendar... again Google Calendar's event's drag'n'drop functionality stopped working... again, after nearly exactly two years since previous report. Tried to restart both Google Calendar and phone itself (Motorola Moto Z2 Play with Android 8.0.0), cleared app cache and then data, without any results.
I did very little to my phone before that happened:

no configuration changed,
nothing actually doing with my phone.

I have only installed one new up -- FakeStandby -- as suggested here, but since this app has nothing to do with the calendar itself, I would be surprised, if that would be a source of the problem.
To clarify problem:
On a day view (not: agenda) long-pressing any event now brings no effect. Previously it caused an event box to be risen up visually above others, and moving finger around screen allowed to move event to some other hour or day. Now, drag'n'drop functionality does not exist / does nothing.
Is there any know report about some bug, bug's regression or is this a generally known problem? Or is this again my stupid phone going wako in exactly the same way during second anniversary of the moment, this problem appeared for the first time?
EDIT: From what I have learned, when Calendar becomes &quot;locked&quot; (no event's drag'n'drop) all items in calendar are visually more flat than usual. When functionality &quot;returns&quot; they again become a little bit 3D-like.
On contrary to initial believes, it was (is) FakeStandby that is causing these problems!
This app is designed to FakeStandby mode, by turning off screen, but not causing actual standby mode. This causes that all other apps are not notified about phone being in standby and continue working in background (below FakeStandby).
To achieve this, FakeStandby must be able to control all apps (at least that's what its author claims). And in order to do so, it adds itself to the &quot;Accessibility&quot; section of the configuration:

And... that's all. Having FakeStandby Service turned off causes Google Calendar application to lose / disable / turn off event's drag'n'drop functionality. Why? Unfortunately, I have no idea.
The simplest workaround -- for having Google Calendar's full functionality and not being forced to uninstall FakeStandby -- is to kill this app after each use. Long-press on its icon &gt; App Info &gt; Force Stop does the magic. Until next run of FakeStandby, Google Calendar will have full functionality.
Since this is a system service, killing it with Force Stop will also automatically reset its setting in Accessibility &gt; Downloaded Services to Off. When you run FakeStandby next time and attempt to activate it (by pressing its button on the right side of the screen) you will see a message:

If this is too annoying for you or impractical, because you're using FakeStandby too often then I think there is no other option rather than a split decision:

find some FakeStandby replacement or
stop using drag'n'drop functionality in Google Calendar.

I am pretty sure that this is some kind of bug in FakeStandby itself, not in Google Calendar. As I have two other apps listed in Accessibility &gt; Downloaded Services (namely: Nova Launcher and Kaspersky Safe Kids). Both apps has their setting set to Off by default (because ability to observe screen and control other apps is used in them only in a rare, specific scenarios).
But, I have just managed to test that setting it to On for any of these two does not cause described problems with Google Calendar. So this got to be &quot;something&quot; in between FakeStandby and Oreo (I have no ability to test this issue in other versions of Android system).