just bought a ticket on united with a flight on austrian EWR-VIE. fared it in B so i could use miles to upgrade to I. it cleared immediately, but now i get the dreaded notice in red "call us to reissue your ticket." which i did, and agent says nothing to worry about, because of the *A upgrade it will always show like that and that i will need to check in at the airport. the problem is that the flights are showing at the wrong times (for dep and arr) and date (arr).
DEPARTURE
Sun, Feb ##, 2019
12:00 AM [wrong time!}
EWR
ARRIVAL
Mon, Jan 01, 2001 [definitely wrong date and time!]
12:00 AM
VIE

when i check the OS website with the OS PNR, flight shows fine. is this a common/known issue and really nothing to worry about? tia

As long as (a) the OS PNR is in order and Austrian can confirm this, and (b) there isn't a duplicate Economy/Business pair of segments on the UA end, you should be good to fly.

this is completely normal.

How can one ever be completely sure in these post-Saudi days though?

Having personally experienced what happens when a ticket isn't synced correctly (albeit on OAL), I'd try a few different agents having a look at it before going to the airport.

@OP these red messages tend to clear after a few days. I'd only be concerned if they stick around for longer than a week. You're right, however, to never trust an agent saying "there's nothing to worry about". That agent won't be at the check-in desk when the system refuses to print your BP.

You can never be sure, but neither will HUCAing and getting three different stories from three different United agents help. The general guidance is if the operating carrier sees the coupons as good in their record, you can fly regardless of the state of the record on the non-operating carrier. (Best you can confirm this is to talk to a reservations agent of the operating carrier.)

The only time I've had this lead me astray is when UA failed to clean up the record and had active segments in both classes on my UA PNR, and this prompted the computer to cancel my higher-cabin segment. LH saw it as an issuer-initiated cancel, so I had to conference call with UA and LH to fix.

Previous times I had ridden UA red text to the gate (every UA agent insisted it would be fine, so no way to clean it up) and flew without issue.