Strange Excel VBA -> Access behaviour

I have an excel table that is not shared and is used by 40 people approx. In that excel i have VBA macro so when someone changes a cell, that macro saves that value in access and makes that value locked.

What is by your opinion best way to present user that value IS saved (msgbox is out of the question) and what is saved and how to even check that?

Currently my macro is doing this:

Value is changed, changed event is fired, excel opens connection to database, it forms sql command, saved that value in database, then it delete value in a cell, runs sql select query for that recordset and presents that value in that cell. So basically if user enters something, if cell empties, value is not stored. But ... there is but. I have some users reporting that it did show value but after reopening an excel file (while opening it retrieves everything) those values are not there.

What do you think how to solve it?

I even considered that when user finished, it clicks button save and macro goes line by line and just saves everything that was changed. But ... that would be a lof of queryies ad once, and I cannot build bigger query than 1024 characters if I understood MSDN correctly. Any suggestions? per user I have at least at once 120 records filled up.