Hi @Matias_Furgiuele, welcome to the community!
I am so sorry to hear you’re having trouble here. I gave this a go on my side and could indeed not activate the workflows via the CLI as expected 
. I got a slightly different behaviour though ( n8n update:workflow --all --active=true returning a Deactivating all workflows message), could you perhaps confirm which version of n8n you have tested this with?
We also have another open bug related to the CLI and this sounds like it might be related. I shall add your report to our internal bug tracker as well and we’ll of course get back to you as soon as this has been looked at.