In full offline when you place a woven echo into the timeline you instantly get one added back so you basically have an infinite amount of woven echoes for free.
Other reports of the same bug:
Update: I just realised that the bug happens on my Asus ROG Ally when I place woven echoes with the integrated gamepad, but it seems to work correctly when I place them with a mouse - the woven echoes are taken away when using the mouse.