Unable to edit my posts on Instagram

Hello everyone,

I have been experiencing a small problem with my Instagram account since last night: I wanted to add my account name as a hashtag at the end of each of my posts (which total 380), but after modifying about 150 posts, I received a message (see screenshot) that now prevents me from modifying any post on my account...

Are other people experiencing the same issue? And more importantly, what can I do to get the feature back?

Thanks in advance! ;)