The reasons for the delay are, according to the Facebook message, "problems with the material". The newsletter adds that Pandastorm believed the german dub to exist but realised too late that it had been deleted. Thankfully a fan helped out with his recording of the german dub.
Here is the original newsletter announcement, translated from German:
Dear Doctor Who-fans,
we received a lot of positive feedback from you for the last few months. There were photos with you and the boxed sets, a self-made action figure of the Candyman and even Sophie Aldred (Ace) who can be seen on a picture, posing with our second 7th Doctor boxed set. WOW! We would like to send you all a big THANK YOU. Without you the making of these boxed sets would not have been possible.
Some of you might already know that we will also release "The Five Doctors" in Germany. We planned to release it on 26th June 2015 but we sadly have to delay the release to 28th August 2015. After some misunderstandings we now know for sure that the German TV-version had been destroyed. The good news is that our appeal to fans last summer payed off after all and a Doctor Who-fan made his recording available to us. All this took us a lot of time, so that the DVD's won't be ready in time, if we want to deliver a high quality product.
Pandastorm then continued listing all the versions of the 20th Anniversary Special that will be on the 2-Disc-Set:
So far Pandastorm Pictures released all three seasons of the seventh Doctor in season boxed sets in Germany. After The Five Doctors they are going to release two boxed sets for the complete sixth Doctor run and a 2-disc DVD release of The TV Movie.
- TV version in English
- TV version in German (including German subtitles for the scenes edited out in Germany)
- Three-part TV version in German (heavily edited, some scenes arranged in a different order)
- Special Edition in English
- Special Edition in German (including German subtitles for the scenes that were not shown in Germany)