There is a conflict with the PWM output on A15 (TS_CH1), possibly caused by SPI3_CS (HW CS for SPI slave mode). The CS slave pin may or may not be the problem, though.
This pin is not used as CS on the SPI flash connected to SPI3, but the HW/Slave CS functionality may be getting configured or set by the multiplexer with the SPI flash code.
In any case, the config or multiplexing issue should be resolved to enable PWM on A15 again. Further investigation required.
There is a conflict with the PWM output on A15 (TS_CH1), possibly caused by SPI3_CS (HW CS for SPI slave mode). The CS slave pin may or may not be the problem, though.
This pin is not used as CS on the SPI flash connected to SPI3, but the HW/Slave CS functionality may be getting configured or set by the multiplexer with the SPI flash code.
In any case, the config or multiplexing issue should be resolved to enable PWM on A15 again. Further investigation required.