When I slave the Tempest to ANY other midi clock source, it has a LOT of clock drift. I bought this used, but System info is showing I'm on OS 1.4 and voice 1.5.
As this was a function important to me, I checked this out on the current official OS and various beta's this past year. Specific user configuration issues aside, I have found Tempest to not have perceptible drift when it slaves via direct USB connection to Logic under normal loads.
(When pushing the system to extremes, I could hear momentary drift, but quickly locking in again. Those extreme loads include exceptionally high tempos, and excessively busy sequences. I discount those. So, from my observation, the particular sync I've described is solid.)
I believe this is an aspect important to DSI, and will exist in the last OS.
My suggestion would be to update to the current beta OS. It's all but final. Moreso, as you are new to Tempest and do have a body of work behind it; and I assume are not knee-deep in a project and must keep functional that which is needed for that project.
When I set it as slave, it will show BPM wit an added .1, i.e. BPM at 120.1 instead of 120. Occasionally it will appear to sync when I set BPM to 117.5 or 119.5, but then it will drift up and down in BPM as it plays. Was this an earlier bug?
This is not a bug. This is intentional behavior. Sonically, sync is tight. Visually, there's variance between the Tempest tempo readout and the other device's tempo readout. I don't know the exact reason. (There's a possibility it's related to focusing on actual sync, with less emphasis on always matching visual.) It could be disconcerting until you are told it's normal. But, your ears could easily tell you what's what.
I can't seem to find any info on midi clock drift when googling and digging through the forums.
In conjunction with my personal tests, I figure that supports the absence of this as a current issue. As I find this feature essential, I am always curious to read about other's experiences with it.
Also is there a "search" function for the forums I'm not seeing?
There's one in the top left screen, 3rd word from the left, in between "Help" & "Profile", you'll find "Search".
Of course, there's the ever-useful
[query terms] site: xyz.com
Where xyz in this case = forum.davesmithinstruments.com