Propanoic acid reaction with potassium permanganate
Can you detail the concentrations of both the acid as well as $\ce{KMnO4}$ and also the time it took to de-colourise?

I tried an experiment however, I only have Glacial Acetic Acid, which didn't seem to react ( as the smell was still prominent).

I can suggest you a simple trick to analyse whether it is decomposing. Smell Propionic acid before adding $\ce{KMnO4}$. Then smell it after the colour of $\ce{KMnO4}$ is gone. Keep adding $\ce{KMnO4}$ till the pink colour stay(similar to titration). Then smell again. If the smell is gone then the carboxylic acid is oxidised.

There are 2 possible oxidation products of carboxylic acid:


Ketone
Carbon Dioxide


Both can be pretty obvious. Ketone will smell differently than the acid(more like nail polish remover) and Carbon Dioxide should be visible because of effervescence.