Format of Title changed with version 9.1 ? Bug ?

Hello 

as a keen birder, I have a multitude of pictures of birds which I classify by Bird family(as title), bird name(as caption) ,date of picture taken and eventually sequence.

I used to use the EXPORT function and do a rename of the DNG picture into a new Jpeg file name.

As Title I had the format like as example 23.100, which would mean bird#100 out of family #43.

So my resulting new Jpeg file name would be 23.100-birdname,date-sequence.Jpeg.

However with version 9.1 this does not work anymore. ! ( Not sure when the change occured as I went recently from 6.4 standalone- which is OK , to classic 9.1)

The title with such a numerical format is ignored when I edit the Rename Preset like {title}-{caption},{date}-{sequence}.When I leave out title in the previous string, the rename works ( obviously with just caption,date and sequence).

If I leave it in the string, just the first numerical digits before the dot , in the example 23, are shown, without caption, date,sequence !

If I change the title from 23.100 to 23100, then the whole rename is done correctly .

Is there a way to force LR to accept titles with numerical format xxx.yyy ? like it was possible before ?

I have thousands of pictures thus classified into 200+ bird family folders with pictures in sequence as described above  and I would like to maintain this system which was simple and ran smoothly before.

Booth Lighroom and Windows sort by such a format of filename.

What are my options ?

Thank you 

Marc