So, as mentioned in the comments, there's a bug where raids won't trigger with the new quest system. I've think that I've just found a possible clue to why this happens...
Apparently, incoming raids get stored inside of the save file. Now, the bugged raids look like this:
<incidentQueue>
<queuedIncidents>
<li>
<firingInc>
<def>RaidEnemy</def>
<parms>
<target>null</target>
<threatPoints>19421.7</threatPoints>
<faction>Faction_2</faction>
<forced>True</forced>
<letterHyperlinkThingDefs IsNull="True" />
<letterHyperlinkHediffDefs IsNull="True" />
<spawnCenter>(94, 0, 172)</spawnCenter>
<spawnRotation>2</spawnRotation>
<raidStrategy>ImmediateAttack</raidStrategy>
<raidArrivalMode>CenterDrop</raidArrivalMode>
<pawnGroups IsNull="True" />
<podOpenDelay>520</podOpenDelay>
<quest>Quest_44</quest>
</parms>
</firingInc>
<fireTick>47408797</fireTick>
</li>
</queuedIncidents>
</incidentQueue>
But a normal raid should look like:
<incidentQueue>
<queuedIncidents>
<li>
<firingInc>
<def>RaidEnemy</def>
<parms>
<target>Map_0</target>
<threatPoints>19421.7</threatPoints>
<faction>Faction_2</faction>
<forced>True</forced>
<letterHyperlinkThingDefs IsNull="True" />
<letterHyperlinkHediffDefs IsNull="True" />
<spawnCenter>(94, 0, 172)</spawnCenter>
<spawnRotation>2</spawnRotation>
<raidStrategy>ImmediateAttack</raidStrategy>
<raidArrivalMode>CenterDrop</raidArrivalMode>
<pawnGroups IsNull="True" />
<podOpenDelay>520</podOpenDelay>
<quest>Quest_44</quest>
</parms>
</firingInc>
<fireTick>47408797</fireTick>
</li>
</queuedIncidents>
</incidentQueue>
As we may see, the target of the first one is a null map, while it should be the map of the quest, e.i. map_0, in my case. It seems to fix individual events, and it has to be done with every quest incident. Hope this helps in fixing the glitch...