Hi,
There are 2 major scenarios in which the breakpoint might not be set:
1. The project was built without debug information (but I see above you also tried debug configuration - so this seems is not the case)
2. The project was build but the source location in binary file does not correspond with the current source you are trying to set the breakpoint (for instance the project was built on another machine or from another source location). For this, try a clean + rebuild the project.
If this doesn't work, please try to go into debug with "debug configuration", double click on the stack on "main" function in order to open the main.c file:
- check this file has the same filepath as the source you initially tried to place the breakpoint
- check if you can set the breakpoint in this file that was open.
Greetings,
MCUXpresso IDE Support