Hello there ! First post here as I have started my Blender journey not so long ago !
Learning modeling with simple exercises, while I try to master the basics of blender.
I have a “weird” issue with the bevel tool, where it do not go as expected, but with tris-spikes. I am not using the bevel modifier (FWIW) but the “classic” tool (please, don’t roast me, I am new here 
).
I do have already merged vertices --by distance-- and applied the scale on object mode : the issue remained.
I really am just learning the software, so I do not fully understand the reason behind that behaviour, so I’d be really happy to get both solution and explanation 
Have a great day, fellas !
[edit] Oh, I am adding the .blend, that might be more usefull than a simple screenshot : https://tinyurl.com/y5h7gjka
Hi nooxouille ! I used your file and it works well on my computer (last blender version on steam, almost no addons). Maybe it was because of your version and the flipped normals (I flipped them outside but the bevel was working with inside normals). I attached the file
Edit : to check the normals you can click on the “overlays” arrow icon on the mid-right top of the screen and go to geometry>face orientation
training-editmode.blend (1.7 MB)
Hey ! Thank you for your quick anwser
Somehow, upon creating a new mesh within the same .blend that I provided you, the issue happened again while trying to redo the apple from scratch.
Closing the app, and restarting it aaaaaaaaand … it’s gone.
I don’t understand the reason behind this tho.
Blender is up to date, on the latest MacOs version (apple silicon).
So it is working again but if anyone as more detailed explanations, let me know !
