Hi,
welcome to communities!!
From researching, it looks like there is absolutely no way to get around this except to redo the datastore. Is this correct?
yes, unfortunately there is no way to change the blocksize of vmfs datastore without reformatting.
If it is, I was looking at a way to save the three current machines and reload them after it is refreshed. One way that I thought of was to go browse the datastore and copy all of the files over to my local machine for the VM (.nvram, .vmdk, .vmx etx...all files), wipeout and redo the ESXi host with the correct datastore setting, build the VM machines in vSphere and then replace the files with the copied ones. Will this work fine? I
yes, it will work. You just copy all the folders in this VMFS datastore to a safe location and upload it back once the block size increased. Once upload compleated, go to VM folder, right click the VM and Register the VMX.
you can find the steps to change the VMFS block size in this KB. VMware KB: Block size limitations of a VMFS datastore
