Time taken to solve depends on the ordering of vehicle capacity

[aniketsharma00411]

What version of OR-Tools and what language are you using?
Version: 9.0.9048
Language: Python

Which solver are you using (e.g. CP-SAT, Routing Solver, GLOP, BOP, Gurobi)
Routing Solver

What operating system (Linux, Windows, ...) and version?
Linux Mint 20.1 Cinnamon

What did you do?
I have tried to create a CVRPTW solution by combining CVRP and VRPTW from examples provided in the official documentation.

I am sharing a colab notebook demonstrating a short example reproducing the problem:
https://colab.research.google.com/drive/1YN-6kABqGqSkQKxOtWD6YA2ZDlP8RfqD?usp=sharing

The quantities to deliver at each node are [0, 80, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1]

I have 22 vehicles, 21 vehicles with capacity 25 and 1 vehicle with capacity 600.
If the vehicles are sorted in ascending order the example with 14 nodes take more than 200 seconds to solve and if they are sorted in descending order the same example gets solved in less than a second.

I am using Google OR Tools for the first time so I don't know if this was expected or not. I have tried adding Guided Local Search also but when I add a time limit to stop it stops without giving a solution.

I have asked this question in Stack Overflow also.

https://stackoverflow.com/q/67570171/8550821

I have also asked this question in the official mailing list.

https://groups.google.com/g/or-tools-discuss/c/MHoMwkHQuoo

[aniketsharma00411]

As per the suggestion given by Laurent Perron in the mailing list, I have tried using different first solution strategies.

It works properly when using SAVINGS, PARALLEL_CHEAPEST_INSERTION, and LOCAL_CHEAPEST_INSERTION.