Here I list some frequently-asked questions and my answers for them.

Note: If you cannot find a solution to the problem you found in this page, chances are that the problem is not well-understood enough that there is no definite solution/answer available. Go check the Known Issues in that case.

This is IPT2's problem. For those using Transport Line Manager (TLM) you will notice things are working just fine.

IPT2 has a configurable option named "unbunching aggressiveness". To quote from their Workshop description:

Note: if you feel that unbunching doesn't work as expected, go to mods options and check aggression setting. 52 equals to vanilla aggression. Other than allowing to enable/disable unbunching and setting aggression setting, this mod doesn't deal with unbunching. If you have issues with unbunching, ask Colossal Order how to fix them.

From my past experience of using IPT2, setting unbunching aggressiveness to 3 is a good value for buses to properly unbunch and not stay at bus stops for too long.

Technical information:

This mod does not modify any unbunching logic, but rather "disconnects" them from the game when certain conditions are met. The exact behavior of unbunching depends on the mod(s) that you use (if any).

You may refer to the GitHub readme here for more information: https://github.com/Vectorial1024/ExpressBusServices

It means Harmony failed to patch a file, or, this mod failed to properly detect Harmony, and so things behaved very unexpectedly. Frustratingly, it does not appear for everyone. Some may have this error, while some may have totally no problem.

2021 Feb 16 update:

To alleviate this problem, this mod leverages the CitiesHarmony mod to obtain the well-accepted version of Harmony of the Community. Still, this mod DOES NOT auto-subscribe to CitiesHarmony out of security concerns.

However, CitiesHarmony may sometimes release updates which are not backwards-compatible. I trust the guys at CitiesHarmony are trying their best to bugfix CH, since the complexity of CH to provide compatibility to older versions of the HarmonyLib is not trivial. Still, in such cases, until I react to those updates and provide an update on this side when time allows, you are strongly suggested to head to CitiesHarmony's support threads for more information and possible fixes. Note that, depending on the actual technical details of the CH updates involved, it is possible that the only option is to wait it out.

This error means that this mod failed to detect IPT2, possibly due to load order problems. While, hopefully, this kind of error will not happen anymore, still, just in case, I provide some proposed fixes to fix the loading order by hand (Cities Skylines does not provide any official way of resolving load order).

PC28K's Proposed Fix

I slightly modify their proposed fix to make it clearer.

1. Subscribe to the v2 Harmony (already listed as a Steam dependency)
2. Wait for Steam to download the v2 Harmony
3. Copy the v2 Harmony to the "local mod folder" (See https://skylines.paradoxwikis.com/User_path) (paste it to Addons/Mods/)
4. Unsubscribe from the Workshop version of the v2 Harmony, and completely rely on the local Harmony copy

It should probably work because it is hypothesized that mods in the "local folders" have a earlier load order.

Vectorial1024's Proposed Fix

This is best done in the in-game mod manager for convenience.

1. Unsubscribe from this mod
2. Unsubscribe from the v2 Harmony dependency
3. Unsubscribe from IPT2
4. Restart the game
5. Subscribe to the v2 Harmony dependency again
6. Subscribe to IPT2 again
7. Subscribe to this mod again
8. Restart the game

This should probably work because it is observed that newly added mods are loaded last, and by doing this, we can help place the v2 Harmony (and also IPT2) in the correct load order position.