Getting a new vendor can be one of the many reasons to implement new HR technology. A new vendor typically starts out focused on proving itself and pleasing its new customer. The relationship typically gets off to a good start.
But then, something happens that jeopardizes the relationship. It may be fixable and not too serious, like a task completed a little late or other misstep during the implementation. Or it might be something later and more serious, like a service delivery error or multiple missed SLAs.
The vendor then starts communicating less frequently. Meanwhile, the customer notices that the vendor has become quieter, and starts wondering if the vendor oversold its capabilities. This of course doesn't help the relationship or help the parties reach their mutual goals.
The solution to this dilemma can be transparency by the vendor: prompt disclosure with a plan to fix. This is often the best way to diffuse the parties' chess-game feelings of second-guessing, fear of not noticing, and concern about being surprised by the other party's next move.
Having been on the vendor side, I understand the reluctance to come clean quickly. I've been there, including to assess problems and figure out plans to disclose and fix. In my experience, it's better to stay ahead of the problem. The customer appreciates the candor, and some problems are easier solved with the customer's help. Almost all HR problems are easier solved when addressed sooner rather than later.
The customer may be disappointed, but usually remains hopeful that it made the right decision and the vendor will still perform well. The disclosure shows the customer that the vendor is upfront and minimizes surprises -- and doesn't play games.