Elevator glitch
Whenever I load my map, I start in the elevator, sometimes the elevator works correctly (goes up and opens), and sometimes I start trapped in an elevator that won't move. Can someone help me resolve this issue?
Can you give some more information?
Did you make the map yourself in hammer?
Did you use the default instances?
etc etc.
I made my map in hammer. I followed a tutorial on youtube to create it. I can post the video, if you think you might need it. Here are the instances I used:
instances/turbine_elevator/arrival_elevator_a4_logic.vm
instances/turbine_elevator/arrival_elevator_a4_base.vmf
To create the elevator, I first made the base, then copied and pasted it (I may have created a new instance, I can't remember it exactly)then I made the logic and made it overlap. Then I grouped them together. Let me know if you need more info.
This problem has been mentioned a few times before and actually happened quite frequently. I believe it had something to do with automatic map behaviors with the transition script and it not executing the correct command when the map started (however a restart of the map would work).
This should have been updated and fixed with the PTI update as the command to start the elevator is actually executed by a trigger when you spawn inside the elevator.
If your arrival_elevator_a4_logic does not have this output when you edit the instance, then I suggest deleting / moving the file from your instances/turbine_elevator folder and then verifying the cache of Portal 2 Authoring Tools.
Alternatively you can force the elevator to move by creating an output. Copy the output to start your elevator and paste it inside a logic_auto. Remember that instances are automatically named, so give your instance a Fix Up Name and instead of the output pointing towards elevator_1, point it towards WhatEverYouNamedTheInstance-elevator_1.
e.g. OnMapSpawn > WhatEverYouNamedTheInstance-elevator_1 > MoveToPathNode > @elevator_1_bottom_path_1
Hmmm.... with "copy/paste" you mean "Shift + Drag", right? because copy/paste could lead to problems... The correct way to go is to use the TOP view, shift-drag the "base" instance a bit to one side (just some units only), make the new instance be pointing to the "logic" .VMF and make it overlap the previous one (or firstly to place the 2nd instance overlapping, then change the .VMF to the "logic" elevator instance)... Just a tiny "misoverlapping" can lead to random errors...
Also, I guess that you added the arrival_departure_transition instance, right? did you edit it in some way?
useful tools and stuff here on TWP 
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Do you have a player start inside the elevator? If so, then that will cause exactly this problem.
(Technical background here.)
The already mentioned arrival_departure_transition_ents instance has a player start in it (so you don't need to place one manually), and it will teleport the player into the elevator on map start and activate it correctly.
If you don't want to use that, then just force the elevator to start with a logic_auto, as ChickenMobile explains.
Other Portal 2 maps: Medusa Glare
Portal 1 maps: Try Anything Twice | Manic Mechanic
Thanks for your help everyone. The video didn't say anything about that instance, or I just didn't watch it long enough. That instance was all I needed.
Was it SkwittGaming or whatever? He has nice tutorials, but they're not perfect, and I'd suggest rocketrascal24 (TopHattWaffle) or Solarchronus.
(Technical background here.)
The already mentioned arrival_departure_transition_ents instance has a player start in it (so you don't need to place one manually), and it will teleport the player into the elevator on map start and activate it correctly.
If you don't want to use that, then just force the elevator to start with a logic_auto, as ChickenMobile explains.
I was having this problem too. I was putting a player start in the elevator and when it didn't work, I guessed this was the problem, but I didn't know about the instance.