Unable to debug binaries in embedded cross-compile (QEMU, gcc-arm64)

It is very non-trivial to build Qt correctly to be able to debug it on QEMU-powered arm64. Currently I experience issues with the yocto debugger as if my binaries lack debug info.

The steps to reproduce:
1. Prepare VM (see Linux QEMU (gcc-arm64) on Linux Ubuntu_18_04 (gcc-x86_64) in Coin)
2. Connect to the VM, git clone Qt (dev branch) from code.qt.io
3. Configure & build (used out-of-source build):

configure -opensource -confirm-license -verbose -debug  -nomake examples -no-compile-examples -openssl -device linux-generic-g++ -device-option CROSS_COMPILE=/opt/yocto-arm64/sysroots/x86_64-pokysdk-linux/usr/bin/aarch64-poky-linux/aarch64-poky-linux- -device-option DISTRO_OPTS=boot2qt -sysroot /opt/yocto-arm64/sysroots/aarch64-poky-linux -extprefix /home/qt/work/install -mysql_config /opt/yocto-arm64/sysroots/aarch64-poky-linux/usr/bin/mysql_config -psql_config /dev/null -tslib -no-optimize-debug -skip qtwebengine -skip qtpim -no-pch -make tests

This configuration claims to build in debug, also "-g" compile flag is visible during make stage
4. Set up environment as in QEMU debug instruction
5. Running under QEMU is successful. For example:

./target_wrapper.sh qemu-aarch64 ./tst_qdatetime

6. But debugging is not (see QEMU debug instruction for steps clarification).
To wait for debugger connection:

./target_wrapper.sh qemu-aarch64 -g 1234 ./tst_qdatetime

Attaching the debugger is done via:

target remote localhost:1234

I can successfully attach and set breakpoints. However, running the binary ("continue" command in this setting) ignores all the breakpoints. It looks as if I have a build with no debug information and thus the debugger is unable to break where requested. However, I can clearly see from the build log that "-g" option is used. Also, tests claim that configuration is "debug build" when executed.
Attached debugger log, looks rather OK to me (no errors visible).