Understanding Society User Support

Hello, I kindly have a specific question related to the "inapplicable" category within the missing values. Let me please move a step back and explain. As I am particularly interested in the "hcond" variables in combination with other political variables across waves, in Stata I have appended all files named "indresp" by first removing the wave prefix from each variable (e.g., "a_" for wave 1). I hope this was the right way to go. Please do let me know if I should have also considered other files than indresp. What is not very clear to me is the reason why, when for instance cross-tabulating one of the hcond variables (hcond17) with vote3 in wave 1, roughly half of the sample ends up in the inapplicable category (i.e., 23,616 out of 50,994). I have a similar question but across waves. When tabulating hcond17 for wave 1 and wave 3 (as the question was not asked in wave 2), the inapplicable category is only present in wave 3 and not in wave 1. Most importantly, out of a total 49,739 observations, 43,324 fall in the inapplicable category. So, I wanted to be sure about the reason why I am losing so many people in subsequent waves and what this inapplicable category really means (for instance, does it refer to particular categories of respondents and, if so, which ones?). I have attached the screenshots for you. Meanwhile, please do not hesitate to contact me if you have any questions or doubts regarding the way I appended the data. Thank you very much in advance and I look forward to your reply.
Luca