I have previously used K3B to back up my home directories to DVD+RW.  Now when I try to write new backups onto the used media the Burn dialog, the Burn Medium selection says, "Please insert a suitable medium" and the Burn button is disabled.



Reproducible: Always

Steps to Reproduce:
1. Open K3B
2. Insert used DVD+RW
3. Create a new Data project
4. Add some data to be written
5. Click on Burn
Actual Results:  
In the Burn dialog window, the Burn Medium selection says, "Please insert a suitable medium" and the Burn button is disabled.
(With K3B 1.0.5, the Burn Medium selection says, "Please insert an empty or appendable Double Layer DVD±RW medium" and the Burn button is disabled.)

Expected Results:  
Since the media is rewritable, and K3B itself (both versions) says that no special formatting is required (No need to format DVD+RW media more than once.  it may simply be overwritten.), the burn operation should proceed.

Media Info shows:
Medium

Type:	DVD+RW
Media ID:	INFODISC/A10
Capacity:	510:01:29 min (4.4 GiB)
Used Capacity:	337:49:19 min (2.9 GiB)
Remaining:	172:12:10 min (1.5 GiB)
Rewritable:	yes
Appendable:	yes
Empty:	no
Layers:	1
Background Format:	incomplete
Sessions:	1
Supported writing speeds:	2.4x (3324 KB/s)
4.0x (5540 KB/s)
ISO9660 Filesystem Info

System Id:	LINUX
Volume Id:	BU2012-03-09.2
Volume Set Id:	-
Publisher Id:	-
Preparer Id:	-
Application Id:	K3B THE CD KREATOR (C) 1998-2010 SEBASTIAN TRUEG AND MICHAL MALEK
Volume Size:	2.9 GiB (2,048 B * 1,520,194 blocks = 3,113,357,312 B)
Tracks

Type	Attributes	First-Last Sector	Length
1	(Data)	no copy/uninterrupted



So I tried using Tools=>Format/Erase rewritable disk... but it says:
Checking medium
Found DVD+RW medium.
No need to format DVD+RW media more than once.
it may simply be overwritten.

but the Burn button is still disabled.

When I tried reformatting with the Force option (with or without Quick Format), I see:
Checking medium
Found DVD+RW medium.
No need to format DVD+RW media more than once.
it may simply be overwritten.
Forcing formatting anyway.
It is not recommended to force formatting of DVD+RW media.
After 10-20 reformats the media might become unusable.
Using dvd+rw-format 7.1 - Copyright...
Formatting successfully completed
Do not be concerned with the progress stopping before 100%.
The formatting will continue in the background during writing.
Ejecting medium...

but the Burn button is still disabled.