Quite a few cases, especially the sexual assault ones arriving recently have involved text and chat messages as potential evidence against the client.
As is to be expected, most of the time the investigators do not seize and clone the phone to preserve evidence (although I am dealing with one CID office at Fort Lee that has done that with one of several phones). This is a failure to investigate, and as always is to be expected. What they usually do is photograph the “relevant” by their definition texts on the phone screen and nothing more.
Keep in mind that Mil. R. Evid. 106 AND 304(h)(2) apply to these texts and chats.