The solution here ended up being a change of uC from the STM32L series to the STM32U series, meaning a 32 bit timer was available on the same pin.

This however also had issues as Tim 2 Chan 1 did not work, tried on x2 uC, so a short to the next pin and Tim 2 Chan 2 worked fine.

None of the suggested methods (above) using DMA worked, they suffered similar issues to those reported in the question.