When Update PCB from Sch, some pads has no net.

When Update PCB from Sch, some pads has no net. test.7z

DescriptionUbuntu

Steps to reproduce

1. create sch with two hierarchial sheet (See attachment), Update PCB from Sch, this OK.
2. change J1 pin1 and J1 pin2 NET LABEL to any other, like “TTTB+/TTTB-”.
3. Update PCB from Sch, J1 pin1 or J1 pin2 has no net.
4. Update PCB from Sch again, OK

KiCad Version

Application: KiCad

Version: 5.99.0-unknown-4f191ce2c7~125~ubuntu20.04.1, release build

Libraries:
	wxWidgets 3.0.4
	libcurl/7.68.0 OpenSSL/1.1.1f zlib/1.2.11 brotli/1.0.7 libidn2/2.2.0 libpsl/0.21.0 (+libidn2/2.2.0) libssh/0.9.3/openssl/zlib nghttp2/1.40.0 librtmp/2.3

Platform: Linux 5.8.0-49-generic x86_64, 64 bit, Little endian, wxGTK, xubuntu, x11

Build Info:
	Date: Apr 14 2021 08:15:44
	wxWidgets: 3.0.4 (wchar_t,wx containers,compatible with 2.8) GTK+ 3.24
	Boost: 1.71.0
	OCC: 7.3.0
	Curl: 7.68.0
	ngspice: 31
	Compiler: GCC 9.3.0 with C++ ABI 1013

Build settings:
	KICAD_SCRIPTING=ON
	KICAD_SCRIPTING_MODULES=ON
	KICAD_SCRIPTING_PYTHON3=ON
	KICAD_SCRIPTING_WXPYTHON=ON
	KICAD_SCRIPTING_WXPYTHON_PHOENIX=ON
	KICAD_SCRIPTING_ACTION_MENU=ON
	KICAD_USE_OCC=ON
	KICAD_SPICE=ON