I have a small issue when swapping from using a digital/MSO input as trigger, to an analog input as trigger.
Everything works as expected, but the display shows accumulated waveforms, similar to if infinite persistence was set (intensity is still at 50%).
So the probe can be lifted entirely away from the probed test-point, and the aggregated waveforms continue to show on the display, rather than a horizontal line for DC 0V.
Hitting the 'default' button fixes it. But one then has to re-configure the probe settings, timebase, vertical resolution etc.
I am still learning and exploring, so it may be something very obvious.
Without enough information about all things affecting here, it is impossible to answer. Yes I can start speculation like if this and perhaps if this and that...
Please tell enough information. We don't see the things that you see in it and that you know about. At least I don't know any clairvoyants here.
It's also quite frustrating and time-consuming to start asking each impressive thing separately.
Now, for the sake of example, I am asking just one very essential setting. There are three modes of action related to triggering: Auto. Normal. Single.
So I ask, Auto or Normal?
*)Then there are two different modes. DPO (in Siglent "SPO") or traditional DSO. (Acquisition modes: Fast(default, SPO) and Slow (like ancient DSO))
Because your explanation (without screen dump image) I believe Aq. mode is Fast.
If acq mode is Fast and trigger mode is Normal... when trigger disappear you can see last acquisitions... until next trig. (or do something what clears display)
In DPO mode one display frame can include several last acquisitions overlaid
**) (depending signal and scope settings) and if this situation freeze due to missing trigger... you can see this static display on the screen.
If not then it is broken.
*) When trigger mode is Normal all stay on the screen until next trigger.
When trigger mode is Auto. If not Trigger events it start generate automatic trigger. In case when signal trig.. it draw signal... if trig disappear it start display what ever is input. If zero then it display zero. Time delay after Trigger disappear until it start Auto trig is quite short.
**) in some cases with fastest setup one TFT frame may contain up to thousands of sequential last acquisition traces overlaid in one display frame.
If you turn acquisition mode to Slow... one TFT frame can have only one acquisition. (in some case useful setting)
I can not now test if there exist some problem when LA channels in use...
Please next if need more... take screen image where can see exactly what happen including also settings.