Issue detecting lattice peaks of a custom input tif/emd data

I'm trying to use Atomap to detect peaks in the .tif type lattice image that I've loaded as a hyperspy image, as shown in the guide. The image is being read correctly and is even being plotted correctly after being read. However, the command "am.get_feature_separation(s, separation_range=(2, 20), show_progressbar=False)" shows the error "cannot perform reduce with flexible type" as you can see the enclosed screenshot. Pls. do let me know what I could do to solve it. I'll very grateful for your help. Thank you!