CMake Export Package Not Working As Expected - cmake

Question

I am working through learning CMake's install commands. I have it pretty much figured out for executables. For libraries there are few additional steps to build and install the required CMake scripts so the library can be used in the following scenarios.
Find and link the library from the local build generated by the current CMake project.
Find and link the library from a common installation location. This is required by 3rd party CMake projects that don't build the library.
I want to build a library called FooBar. FooBar is linked to an executable called App, that is defined in the same CMake project as FooBar.
Here are my CMake files and project structure.
<project-root>
|-app
| |-src
| | |-main.cpp
| |
| |-CMakeLists.txt
|
|-lib
| |-include
| | |-FooBar.h
| |
| |-src
| | |-FooBar.cpp
| |
| |-CMakeLists.txt
|
|-CMakeLists.txt
# File: <project-root>/CMakeLists.txt
cmake_minimum_required(VERSION 3.8 FATAL_ERROR)
project(SampleProject VERSION 0.0.1 LANGUAGES CXX)
add_subdirectory(lib)
add_subdirectory(app)
# File: <project-root>/app/CMakeLists.txt
cmake_minimum_required(VERSION 3.8 FATAL_ERROR)
set(TARGET_NAME "App")
find_package(FooBar REQUIRED)
set(IMPL_FILES
${CMAKE_CURRENT_SOURCE_DIR}/src/main.cpp
)
add_executable(
${TARGET_NAME}
${IMPL_FILES}
)
target_link_libraries(
${TARGET_NAME}
PRIVATE
FooBar
)
install(
TARGETS
${TARGET_NAME}
DESTINATION
bin
)
# File: <project-root>/lib/CMakeLists.txt
set(LIB_NAME FooBar)
set(CMAKE_CXX_VERSION 11)
set(IMPL_FILES
${CMAKE_CURRENT_SOURCE_DIR}/src/Lib.cpp
)
set(PUBLIC_DEFI_FILES
${CMAKE_CURRENT_SOURCE_DIR}/include/Lib.h
)
add_library(
${LIB_NAME}
STATIC
${IMPL_FILES}
)
target_include_directories(
${LIB_NAME}
PUBLIC
$<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include>
$<INSTALL_INTERFACE:include>
)
set_target_properties(
${LIB_NAME}
PROPERTIES
PUBLIC_HEADER
${PUBLIC_DEFI_FILES}
)
install(
TARGETS
${LIB_NAME}
EXPORT
${LIB_NAME}Targets
PUBLIC_HEADER DESTINATION include
ARCHIVE DESTINATION lib
)
install(
EXPORT
${LIB_NAME}Targets
FILE
${LIB_NAME}Config.cmake
DESTINATION
lib/cmake/${LIB_NAME}
)
# I am under the impression these are needed for other targets in the
# current project to be able to use "find_package(FooBar)". I also
# think that "CMAKE_EXPORT_NO_PACKAGE_REGISTRY" needs to not be set.
message(STATUS "CMAKE_EXPORT_NO_PACKAGE_REGISTRY: ${CMAKE_EXPORT_NO_PACKAGE_REGISTRY}")
export(
EXPORT
${LIB_NAME}Targets
FILE
${CMAKE_CURRENT_BINARY_DIR}/${LIB_NAME}Config.cmake
)
export(PACKAGE ${LIB_NAME})
To generate build files I run
# Clean project directory.
mkdir _build
cd _build
cmake .. -DCMAKE_INSTALL_PREFIX=<project-root>/_dist
and I get the following error.
-- CMAKE_EXPORT_NO_PACKAGE_REGISTRY:
CMake Error at app/CMakeLists.txt:5 (find_package):
By not providing "FindFooBar.cmake" in CMAKE_MODULE_PATH this project has
asked CMake to find a package configuration file provided by "FooBar", but
CMake did not find one.
Could not find a package configuration file provided by "FooBar" with any
of the following names:
FooBarConfig.cmake
foobar-config.cmake
Add the installation prefix of "FooBar" to CMAKE_PREFIX_PATH or set
"FooBar_DIR" to a directory containing one of the above files. If "FooBar"
provides a separate development package or SDK, be sure it has been
installed.
-- Configuring incomplete, errors occurred!
Running the above command a second time yields the same error message. I should not see that message because these two lines
export(
EXPORT
${LIB_NAME}Targets
FILE
${CMAKE_CURRENT_BINARY_DIR}/${LIB_NAME}Config.cmake
)
export(PACKAGE ${LIB_NAME})
should generate _build/FooBar/FooBarConfig.cmake and add it to the search path for packages seen by App.
If I remove the app sub-directory, build and install FooBar to _dist, and then re-add app, I do not get the error. Even if I clear out _build and generate build files from scratch, I don't get the error. How is CMake finding my local install config script, but not the one in the build directory? Am I doing something wrong or does anyone have any idea why this might not work?