Firstly, I would like to say that I do not have inside information and that this post is conjecture on my part, but, I thought it important to bring to people's attention.
I am a fan of tabletop gaming in general and am an avid collector, player and fan of Warhammer Age of Sigmar. Today Games Workshop announced that they upcoming Sylvaneth battletome was being delayed by an unforseeable number of months due to a 'bilateral trade' issue that has resulted in an import delay. Their entertaining and honest explanation for this can be found here: https://www.warhammer-community.com/2019/05/08/a-late-bloom-for-the-sylvaneth/
I am unsure if this is a BREXIT related issue, but I suspect it is more likely related to broader world trade tensions with China. The reason for this being is that Games Workshop produces the vast majority of its models, with the exception of some scenery pieces, in the United Kingdom, while other products such as battletomes, dice, etc. are produced in China. Furthermore, Games Workshop's most recent gaming magazine talks about another one of their unreleased products as having been released the previous month.
I should note Games Workshop probably felt obliged to get out in front of this issue due to leaks of the finished Battletome and new dice, spells and scenery appearing online yesterday.
Now, as many of you are aware, FFG Armada miniatures are produced in China which means a similar delay could be in store for us.
Again, this is conjecture on my part but I thought I would put it forward given how notorious FFG has been in the past for communicating delays and the fact that this particular product has already seen multiple delays and still has no firm release date.