Merging zones function doesn't seem to work in any case

Description

When merging two zones an error popup with the message "Zones have insufficient overlap for merging" is shown.

Overlapping the zones does not resolve the issue.

Steps to reproduce

1. Open the attached kicad project PCB
2. Select the two zones, Right-click, Zones -> Merge Zones

kicad-bug-report.zip

KiCad Version

Application: KiCad PCB Editor x64 on x64

Version: (7.0.0-rc1-358-g86c12d35b4), release build

Libraries:
	wxWidgets 3.2.1
	FreeType 2.12.1
	HarfBuzz 5.0.1
	FontConfig 2.14.1
	libcurl/7.83.1-DEV Schannel zlib/1.2.13

Platform: Windows 10 (build 19044), 64-bit edition, 64 bit, Little endian, wxMSW

Build Info:
	Date: Jan 22 2023 06:18:19
	wxWidgets: 3.2.1 (wchar_t,wx containers)
	Boost: 1.80.0
	OCC: 7.6.2
	Curl: 7.83.1-DEV
	ngspice: 38
	Compiler: Visual C++ 1934 without C++ ABI

Build settings:
	KICAD_SPICE=ON