After further testing, it has been discovered that this bug is already resolved. A new issue has been posted with the true issue.
Within the chunk of the world spawn, i tried setting up a clock, that would teleport a ignited creeper to any squid. When a squid is spawned within the region of the spawn chunks, everything works as intended, however, if the player moves out of the spawn chunks, the creeper does not appear. The squid, however, is still detected, and the command block with the command "/tp @e[type=Creeper] @e[type=Squid]" says that the teleport was successful at the correct time. Replacing it with a /say command will provide the text no matter where in the map a squid is spawned.
TLDR: Entities can only be teleported out of spawn chunk as long as a player is within the spawn chunk.
Is this still a concern in the current Minecraft version? If so, please update the affected versions in order to best aid Mojang ensuring bugs are still valid in the latest releases/pre-releases. If this has been done, we can reopen the issue.
Keep in mind that the "Resolved"-Status on this ticket just means "Answered", and that we are waiting for further information on whether this issue still exists or not. We will reopen it as soon as the requested information has been delivered.