error saving

Dear expert,
hello, I am new to FEATool for the first time. I tried to use it to make a case, but there was a problem in the save link “Error saving model:Value must be a handle”. I found that someone raised this problem three years ago. Is it solved now? Yet? It may also be that there is something wrong with my saving method, can you ask me?
grateful

Thank you for trying the software. As for this specific error, we have actually never seen it before, so in order to help we must be able to reproduce it. As such, please read and follow the issue reporting guidelines in the header here. Without more information it is very hard to know what you have done. Could you elaborate the steps you took when you got this error so it might be reproducible.

Hello expert, Thank you for taking the time to answer my question.I just tried this case step by step:https://www.featool.com/model-showcase/01_Quickstart_02_heat_exchanger1/.But actually I get this error, only I can save as GUI script.I will try other cases for further learning.