Answering above question after talking to AC tech support, this has worked now for several "problem patient" accounts.
On the demographics page for a given patient, select and cut the email address, then re-paste it and click the update demographics button. My guess is that cut and past maybe cleans up the email address and then forces the Updox portal to update the record for that patient, and at least sometimes fixes whichever glitch had previously occurred in creating the patient account the first time.
On one patient with no email address on file, I succeeded in creating a working Updox portal account by simply updating the demographic page after making sure email area was empty.
On one patient where above did not work, I cut the email address and pasted to Notepad, updated demographics with an empty email address, then copied and pasted email address from Notepad to demographics and updated again.
Ahh, MU!
