This might be due to hurricanes or dump truck beds tearing down the gantries.
Maybe the Irish Bayou one(*), but definitely not the ones at I-110 in Baton Rouge.
* I just noticed that the Irish Bayou sign is in Clearview. All of the other ones that I've seen (I-10 at I-110, I-10 at LA 49, I-10 at US 165) are in FHWA.
It's possible that DOTD is working on replacing the gantries for these signs but hasn't gotten to them yet. They're well into a major sign/gantry project at the I-12/55 cloverleaf in which all of the old trapezoidal gantries are being replaced. I'd be surprised if these signs are permanent installations--oh wait, this is Louisiana, no I'm not.
