Hi Grzegorz
I don't believe in lucky chances or black magic when developing embedded firmware (although sometimes one indeed has the feeling that there is a mischievous gremlin corrupting things that you are convinced you are doing right, until you realise what are you doing wrong...).
If you open the project in Visual Studio and run the simulator it immediately shows you the problem:

#define UTASKER_APP_START (32 * 1024) // application starts at this address
#define UTASKER_APP_END (unsigned char *)(UTASKER_APP_START + (128 * 1024))
Since your chip has 128k of flash the application range is too large. What is happening is that there is a check at startup to see whether this range is blank and that crashes when checking beyond the end of flash.
The reason why you didn't see this when you had non-blank flash is because the check already quit since it had already found non-blank content - meaning it don't have to check so far and find it crashed.
Since you have RUN_FROM_HIRC enabled it overwrites the crystal settings (if you look carefully you should find these defines are not active and are displayed grayed out by the editor).
Therefore it will be Ok if you change the application size to
#define UTASKER_APP_END (unsigned char *)(UTASKER_APP_START + (96 * 1024))
for example.
Or
#define UTASKER_APP_END (unsigned char *)(SIZE_OF_FLASH - UTASKER_APP_START)
will work if you automatically want to use all remaining flash (although often one keeps an area for saving parameters to that is preserved across firmware uploads).
I checked your LED setup and it is good.
Your force loader switch is not quite right yet and would cause the next crash:
#define SWITCH_4 (PORTA_BIT5)
#define FORCE_BOOT() (!_READ_PORT_MASK(A, SWITCH_4))
There is however nothing configuring the port input before use so you need to also have:
_CONFIG_PORT_INPUT_FAST_LOW(A, (SWITCH_4), PORT_PS_UP_ENABLE);
somewhere.
You can add this to the INIT_WATCHDOG_DISABLE() macro, where the original switch input was being configured.
After this I expect full functionality. When I run it after these modification the simulation shows your chip giving correct USB operation, the LED on PTC2 blinking and the correct input configured:

Good luck
Regards
Mark