[Crystal] rosdep cannot find all required resources

edit

I'm having trouble with rosdep check on 18.04 and Crystal. I've done this:

pip install -U rosdep
sudo rm /etc/ros/rosdep/sources.list.d/20-default.list
sudo rosdep init
rosdep update
cd ~/ros2/orca_ws
. /opt/ros/crystal/setup.bash
colcon build --event-handlers console_direct+
. install/setup.bash
rosdep check orca_base

The output of rosdep is:

ERROR: Rosdep cannot find all required resources to answer your query
Missing resource orca_base
ROS path [0]=/home/clyde/ros2/orca_ws/install/orca_topside/share

orca_topside is one of the packages in my workspace. But why doesn't rosdep know about all of them?

As a workaround, I set ROS_PACKAGE_PATH:

export ROS_PACKAGE_PATH=/home/clyde/ros2/orca_ws/install/orca_base/share
rosdep check orca_base

New output:

All system dependencies have been satisfied
ERROR[orca_base]: Cannot locate rosdep definition for [orca_msgs]
    rosdep key : orca_msgs
    OS name    : ubuntu
    OS version : bionic
    Data: <no data>

Do I need to manually maintain ROS_PACKAGE_PATH for my workspace?

Thanks.

Edit -- the results of colcon version-check

colcon-argcomplete 0.3.2: up-to-date
colcon-bash 0.3.1: up-to-date
colcon-cmake 0.2.7: newer version available (0.2.8)
colcon-core 0.3.17: up-to-date
colcon-defaults 0.2.1: up-to-date
colcon-devtools 0.2.1: up-to-date
colcon-library-path 0.2.1: up-to-date
colcon-metadata 0.2.1: up-to-date
colcon-notification 0.2.6: up-to-date
colcon-output 0.2.3: up-to-date
colcon-package-information 0.2.2: up-to-date
colcon-package-selection 0.2.3: up-to-date
colcon-parallel-executor 0.2.3: up-to-date
colcon-pkg-config 0.1.0: up-to-date
colcon-powershell 0.3.3: up-to-date
colcon-python-setup-py 0.2.1: up-to-date
colcon-recursive-crawl 0.2.0: up-to-date
colcon-ros 0.3.7: up-to-date
colcon-test-result 0.3.1: up-to-date
colcon-zsh 0.3.1: up-to-date