Are all liens invalid if the 45 day window for the NTO has lapsed?

It depends. Generally speaking, yes; if a Florida NTO was sent 45 days past the claimant's first date of furnishing labor and/or materials to the project, the claimant's lien rights are lost.  

But an important thing to note is that the 45 day period runs from the date the supplier in question first provided materials to the project (or when fabrication began for specially fabricated materials); not the project start date itself. Therefore, you should double check the date that the supplier first delivered materials to the project to determine whether the NTO was actually late. 

One other thing to note is that just because you received a preliminary notice, isn't an indication of an actual payment problem. Many contractors and suppliers send a notice on every project, just as a safety precaution if a payment issue arises later on. As long as lien waivers are being collected on the project in exchange for payment, your property will be protected. 

Here are some additional articles you may find helpful:

• Preparing and Sending a Notice to Owner in Florida 
• I received preliminary notice. What do I do next? 
• Florida Notice of Commencement Checklist & Lien Risk Guide for Owners 
• How to Handle Requesting and Tracking Lien Waivers