The better solution is to 'Save As...' the Excel file as a PDF file the way you want it to appear, then 'Place' the PDF into InDesign. A bit more clumsy as you have to 'Save as...' every time you make a change to the Excel file and update the Link to the PDF file, but it is more InDesign friendly.
Can I convert a .pdf created in Excel into a table in InDesign and reformat to my heart's content?
I thought you might want to do that. No, once a PDF you can't edit to your heart's content.
So, as to the matter of thousands of cells? You may have to look that one up but there is a limit on what you can do with an Excel file and InDesign; there are only so many cells, columns and rows that can be imported and let alone worked on inside InDesign.
And you want to merge the cells in InDesign? What ever for? If thousands of cells then edit in Excel to your heart's content and output a PDF. InDesign is not designed as a spreadsheet and not the tool you need and will really bog down with thousands of cells to merge. Just do it in Excel.
I've been placing Excel files into ID and turning them into tables since ID came out. This is the first time I've been unable to place the Excel files. I merge text boxes because it's reader friendly. Check: http://www.wiseco.com/Catalogs/Automobile.aspx click on Domestic Auto Catalog>Ford Pistons.
I see that you are doing catalog work and have many cells you want merged text boxes. Got that.
ID CS5 seems to be unable to support some .xlsx features or just plain doesn't like it. It does seem that CS5 and CS6 has a problem where ID didn't before. I'd try .xls file format if you haven't done so already. Otherwise I'm at a loss as to what is preventing you from placing a formatted Excel file into ID.
I think, until ID can support the formatting in Excel (mainly merging cells), I'm out of luck. I certainly have improved my formatting skills in the past couple of days! :-) I can select and merge "like the wind". I'm glad this catalog is only 140 pages. I truly appreciate the effort you put into trying to helping me out.
I realize this thread is from 2013 but I had the same issue with CS5 and CC versions of ID.
ID still refuses to import .xlsx documents.
Would not place into a text box nor would it directly place into the layer.
That .xlsx was in Excel 97-2011.
However, when I open the .xlsx and ran a "Save As" to convert to Excel 97-2004 (.xls), the Place command worked as expected.
And there's no longer any need to create a text box and then place the spreadsheet within.
Place your 97-2004 .xls directly into the layout and it will behave as expected.
Hope this helps others!