@Silverfish When you connect the solar panel, are there any input watts shown on the screen? You can try to upgrade the firmware to check if the problem can be solved. If not, you can try to replace a solar charging cable to check again. If it still can’t be solved, you can ask for the after-sale service and they will offer you another solution.
Thanks for your response. No input watts (or anything) shown on the screen. The firmware is v1.3.12.
The solar charging cable is new, operates fine when charging other items.
Have contacted after-sale service, they have responded, which I appreciate. Have checked off there suggestions but still no success.
The firmware version looks like: DSP 2052.04… The v1.3.12 is probably the app version, not the firmware. You can check the EB3A firmware version from the firmware update menu.
EB3A is showing current versions ARM v2053.07 DSP v2052.09
I am new to this and have not found how to update firmware.
Please tap the “LOGIN” icon to register your BLUETTI account. Fill in your related information to continue and check if there is any firmware in the page.
Just for your information: The underlying problem can be solved by a simple external capacitor in the solar cable - instead of waiting for new FW versions 
The details are described at the end of this thread:
EB3A Solar input not working
Thank you all for your suggestions and help.
The problem was solved with a new cable.