FiLZ33, thanks so much as your post was invaluable, and i'm sorry you dealt with this! :( I've had a look at the latest build and yes, you're correct; the grenade can't be used in the first Blast Pit map in this build 1.4 of the game.
This is a new problem. I'm currently working on it thanks to you and I'll be uploading a fixed version very soon hopefully.
Agreed that the grenade should be visible too. Hoping to get a bunch more work done on the game this year, including new maps, enemies, set-pieces, etc. without the outdated engine (construct classic) crapping itself and giving me memory overload messages! I would love to add stuff like a grenade in hand / no grenade once the game is finished, and it's a fantastic suggestion.
Thanks heaps for playing & taking the time to post. Greatly appreciated. <3 I'm going to add you to the special thanks credits as FiLZ33 as a way of saying thanks.