Before I write something more pls explain why do you think that cold joint problem affect only high power connections ?please be specific as fare you can, some sources of this judgment will be required I think, because i totally dissagre with You in this matter. Please do not answer by asking me opposite question. That will lead us nothing.
First, I question that a cold joint even exists, and you haven't confirmed that you've disassembled your Solo enough to even make a visual examination, therefore the cold joint theory is entirely speculative.
Second, cold solders can range from insufficiently melted solder but a solid connection nonetheless, to a clear break. In the first case, a break may form over time. The current begin carried by the data wires is so small, that a non-broken but cold joint would have no problem carrying said current. And if there was an actual break, the problem would likely be intermittent as the parts make and loose contact. This could be easily tested without disassembly beyond removing the battery tray by wigging the wire as you test.
Third, the likelihood that a cold joint resulted in a total and persistent lack of continuity, and only on a camera data wire out of all the other power and gimbal data wires seems unlikely just by a matter of odds.
As for sources of this judgement, I can only offer 30+ years of working with/fixing/making electrical things of various kinds, and being a painfully logical problem solver when it comes to diagnosing issues of all types. I've made plenty of bad solder joints over those years. None have resulted in a persistent lack of continuity, always intermittent, if they resulted in issues at all.
Not going to argue or waste any more time. You think it's a cold solder joint based on.... from what you've offered, pure speculation. You can verify that by removing the board and reflowing the joints.
Please report back after you do, I'll be very interested in seeing if that was your problem.