From what I gathered, Solid's current behaviour regarding autofs mounted shares is that: if the share is not currently in use, it will not be listed by Solid regardless if it has been previously mounted and accessed.

Given that some applications (Amarok, Nepomuk, etc.) may keep an index on the content of some autofs mounted folder and rely on Solid to know whether or not this folder refers to a network mounted drive (that might or might not be accessible), the absence of any entry in Solid regarding this location when the share is not being actively accessed will cause those applications to void their index. It follows that when the share will again become available, those applications will need to rebuild their index (which in most case, might be very time consuming).

Once it has detected an autofs mounted share, the correct behaviour for Solid would then be to always keep this share's location in set the StorageAcess.accessible = true/false attribute as appropriate.

Reproducible: Always

Steps to Reproduce:
1. Mount a CIFS share to /somelocation using autofs (with --ghost option)
2. start autofs
3. Access /somelocation (triggering the automount) 
4. Issue: solid-hardware list details in a terminal and confirm that the CIFS entry is indeed listed.
5. stop autofs (and ensure you're not accessing the share's location)
6. Issue: solid-hardware list details in a terminal and confirm that the CIFS entry is NOT listed.
Actual Results:  
When autofs is off, the share is not listed.

Expected Results:  
Solid should always list the share once it's been known to exist and set the  StorageAccess.accessible = true  (bool) attribute as appropriate.

udi = '/org/kde/fstab///192.168.1.150/share/'
  parent = '/org/kde/fstab'  (string)
  vendor = 'share/'  (string)
  product = '192.168.1.150'  (string)
  description = 'share/ on 192.168.1.150'  (string)
  StorageAccess.accessible = true  (bool)
  StorageAccess.filePath = '/home/strav/nas/share'  (string)
  StorageAccess.ignored = false  (bool)
  NetworkShare.type = 'Cifs'  (0x2)  (enum)
  NetworkShare.url = 'smb://192.168.1.150/share/'  (string)