Sharepoint Tab and new file template don't work

[Fsim]

Hi there !

Here is my problem.
I built a sharepoint library to be used for an approval process. This library was created in SP (in the Sharepoint related to a teams) . I added some columns, the approval flow and I only allow the use of an excel template for new files.
In SharePoint, everything works fine.
then I added the Sharepoint library as a new Tab in my Teams channel. (using the Sharepoint tab, not the Sharepoint library). I can perfectly see my files in the correct view. Unfortunaltey, I cannot use the "+New" button. (this worked in Sharepoint)
Clicking on it generate the following message "you'll need a new app to open this about link"
BTW, existing xls file, can be open with no problem.
Only the +NEW button is not working. nor with Excel files, nor with my template.  (nor with any other type of office files)

What should I do ?

kind regards
Fred

ps) Using the Document library Tab, fix the new button behaviour. Unfortunatelly,  my flow is not working anymore and the Library view is no more the default one.

[#2 · Accepted solution]

Its a well known, completely hidden in the documentation issue. Using the SharePoint tab makes everything in that tab read only. That includes the new button. It makes the SharePoint tab a bit useless if you ask me but the work around that Microsoft has told me in the past is to use the document library tab.

I wouldn't like to guess why your workflow is not working.

[#3]

Hi Andrew,
thanks for your answer !
We found a workaround using the management of content types. We set up the template to be used here. Using the + new button now launches the Excel app on the PC. Good enough for me.
fun fact, our SP admin, don't have the issue. he can create a file using the +new button.
Regarding the flow, I'm using the "for a selected file" trigger. This imply a right tab pane to be shown where the user can fill in the parameters for the approval. this right pane don't shows up in the library tab. Moreover, the view is not the good one neither.

[#4]

@Fsim I've found a working solution. If you go to the default Files tab and click the "+ add cloud storage" option, you can select any SharePoint library. 

This library then gets added as a linked folder to the files tab, once you open the folder, you get the templates of that library under the new button, and these work.

[#5]

@TomVanRousselt 
Hi Tom ! I did try that one. unfortunately it don't allow the right pane to shows up when the flow is triggered by the button.
this pane is the result of the first step of the flow.  It works only with the solution I described.

kr

[#6]

@Fsim 

This uservoice describes the same issue but from another perspective: "You'll Need a New App to Open this About" in SPO DocLibrary Website Tab – Welcome to UserVoice!