[REG 5.15.7->5.15.8] remoteobjects/cppclient not compiling on linux, arm64-v8a and x86_64

opt/android/android-ndk-r20/toolchains/llvm/prebuilt/linux-x86_64/bin/clang++ -target aarch64-linux-android21 -fno-limit-debug-info -Wl,-soname,libCppClient_arm64-v8a.so -Wl,--build-id=sha1 -Wl,--no-undefined -Wl,-z,noexecstack -shared -o libCppClient_arm64-v8a.so arm64-v8a/main.o arm64-v8a/moc_rep_timemodel_replica.o   /home/qt/RTA/Qt_5.15.8/5.15.8/android/lib/libQt5RemoteObjects_arm64-v8a.so /home/qt/RTA/Qt_5.15.8/5.15.8/android/lib/libQt5Network_arm64-v8a.so /home/qt/RTA/Qt_5.15.8/5.15.8/android/lib/libQt5Core_arm64-v8a.so   -llog -lz -lm -ldl -lc
make[1]: Entering directory '/home/qt/RTA/Qt_5.15.8/Examples/Qt-5.15.8/remoteobjects/cppclient'
/opt/android/android-ndk-r20/toolchains/llvm/prebuilt/linux-x86_64/bin/clang++ -target x86_64-linux-android21 -fno-limit-debug-info -Wl,-soname,libCppClient_x86_64.so -Wl,--build-id=sha1 -Wl,--no-undefined -Wl,-z,noexecstack -shared -o libCppClient_x86_64.so x86_64/main.o x86_64/moc_rep_timemodel_replica.o   /home/qt/RTA/Qt_5.15.8/5.15.8/android/lib/libQt5RemoteObjects_x86_64.so /home/qt/RTA/Qt_5.15.8/5.15.8/android/lib/libQt5Network_x86_64.so /home/qt/RTA/Qt_5.15.8/5.15.8/android/lib/libQt5Core_x86_64.so   -llog -lz -lm -ldl -lc
x86_64/main.o:main.cpp:function tester::tester(): error: undefined reference to 'vtable for MinuteTimerReplica'
/opt/android/android-ndk-r20/toolchains/llvm/prebuilt/linux-x86_64/bin/../lib/gcc/x86_64-linux-android/4.9.x/../../../../x86_64-linux-android/bin/ld: the vtable symbol may be undefined because the class is missing its key function
clang++: error: linker command failed with exit code 1 (use -v to see invocation)
Makefile.X86_64:264: recipe for target 'libCppClient_x86_64.so' failed
make[1]: *** [libCppClient_x86_64.so] Error 1
make[1]: Leaving directory '/home/qt/RTA/Qt_5.15.8/Examples/Qt-5.15.8/remoteobjects/cppclient'
Makefile:90: recipe for target 'x86_64-all' failed
make: *** [x86_64-all] Error 2
make: *** Waiting for unfinished jobs....
arm64-v8a/main.o: In function `tester::tester()':
main.cpp:(.text._ZN6testerC2Ev[_ZN6testerC2Ev]+0xd8): undefined reference to `vtable for MinuteTimerReplica'
main.cpp:(.text._ZN6testerC2Ev[_ZN6testerC2Ev]+0xdc): undefined reference to `vtable for MinuteTimerReplica'
clang++: error: linker command failed with exit code 1 (use -v to see invocation)
Makefile.Arm64-v8a:264: recipe for target 'libCppClient_arm64-v8a.so' failed
make[1]: *** [libCppClient_arm64-v8a.so] Error 1
make[1]: Leaving directory '/home/qt/RTA/Qt_5.15.8/Examples/Qt-5.15.8/remoteobjects/cppclient'
Makefile:62: recipe for target 'arm64-v8a-all' failed
make: *** [arm64-v8a-all] Error 2