Since the Safari 5.1.5 update, one function of my bank's bill pay can not be accessed and defaults to a different page. I checked with the bank this morning and it seems the latest update of Safari blocks entry into the Medivante bill pay function which operates within the shell of the bank web page. The browser gives no indication that that page is actually from Medivante. Esentially, Safari sees this as a third party and blocks the browser from even getting information, not just cookies!
Bill pay can be accessed from the main page to set up a payment since that is a flow though using the bank information or setup, but is blocked if doing any editing which requires the site communicating directly with Medivante within the bank site.
This can only be gotten around by changing to NEVER blocking cookies. Having the setting of blocking 3rd party and advertiser cookies no longer can be used with the bank site if I need to access the bill pay function. This doesn't even seem to be an issue of cookies, but is blocking access to bank/Medivante information.
Because the never setting is a risky one that only a fool would allow, I have to change the setting while I am in the bank site, change back cookie preferences when done with the bank, then close Safari before I do further browsing (seems the new settings don't always take effect until the browser restarts).
This might be for our protection, but Apple has broken convenient use of the bank site that had worked prior to the update. I do not know who else might be affected. My bank is not one of the "big name" financial institutions but is certainly not a minor instution.