I just received three USB TTL adapters each with a different chipset, and was testing them. 
The CP2102 (I already own one, and it works normally) shows a weird defect: either by connecting it to another adapter (either of the two) or working in loopback, it will not TX data. No led activity, no bytes received on the other side (when it's connected with another adapter).
By chance though I noticed that when I close minicom (Ctrl-A, X, Yes), all that wasn't sent before, gets send at the same time after minicom closed (at least certain amount of data, I tried sending a file in ASCII mode and only a handful of rows of it was transmitted to the other adapter when I closed minicom).

OS is Ubuntu 19.04 64bit, and I'm running minicom as root from a terminal window. Either leaving out the baudrate (defaults to 115200) or setting it explicitly to 9600, the same thing happens.

Is this adapter toasted, and it's good just for RX-only appliations, or is there a way to get it back together?